[Qemu-devel] [PATCH-for-4.1 v4 0/7] virtio-balloon: fixes

[Qemu-devel] [PATCH-for-4.1 v4 0/7] virtio-balloon: fixes

[David Hildenbrand]

As we discovered yet another issue with current PBP code, we decided
to use a temporary PBP only, limited to one series of inflation requests.

Patch #1 is a fix for a wrong sign extension (MST brought this up but
wasn't sure if it is broken - I think it is indeed broken). Patch #2 fixed
QEMU segfaults. Patch #3 and #4 are cleanups that make follow-up fixes
easier. Patch #5 avoids using RAMBlock addresses as tokens and patch #6
fixes all kinds of issues related to using a global PBP. Patch #7 gets
rid of a temporary workaround from patch #5.

We want to have patches 1-6 in 4.1 and backport them to 4.0. Patch #1
needs backports to basically all QEMU releases with virtio-balloon.

Did a quick sanity test, hopefully no other BUG sneeked in. Will do some
more testing.

v3 -> v4:
- Add "virtio-balloon: No need to track subpages for the PBP anymore",
  which doesn't need a stable backport

Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: qemu-stable@nongnu.org

David Hildenbrand (7):
  virtio-balloon: Fix wrong sign extension of PFNs
  virtio-balloon: Fix QEMU crashes on pagesize > BALLOON_PAGE_SIZE
  virtio-balloon: Simplify deflate with pbp
  virtio-balloon: Better names for offset variables in inflate/deflate
    code
  virtio-balloon: Rework pbp tracking data
  virtio-balloon: Use temporary PBP only
  virtio-balloon: No need to track subpages for the PBP anymore

 hw/virtio/virtio-balloon.c         | 120 ++++++++++++++---------------
 include/hw/virtio/virtio-balloon.h |   3 -
 2 files changed, 60 insertions(+), 63 deletions(-)

-- 
2.21.0

[Qemu-devel] [PATCH-for-4.1 v4 1/7] virtio-balloon: Fix wrong sign extension of PFNs

[David Hildenbrand]

If we directly cast from int to uint64_t, we will first sign-extend to
an int64_t, which is wrong. We actually want to treat the PFNs like
unsigned values.

As far as I can see, this dates back to the initial virtio-balloon
commit, but wasn't triggered as fairly big guests would be required.

Cc: qemu-stable@nongnu.org
Reported-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-balloon.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index e85d1c0d5c..515abf6553 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -343,8 +343,8 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
         }
 
         while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
+            unsigned int p = virtio_ldl_p(vdev, &pfn);
             hwaddr pa;
-            int p = virtio_ldl_p(vdev, &pfn);
 
             pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT;
             offset += 4;
-- 
2.21.0

Re: [Qemu-devel] [PATCH-for-4.1 v4 1/7] virtio-balloon: Fix wrong sign extension of PFNs

[Pankaj Gupta]

> 
> If we directly cast from int to uint64_t, we will first sign-extend to
> an int64_t, which is wrong. We actually want to treat the PFNs like
> unsigned values.
> 
> As far as I can see, this dates back to the initial virtio-balloon
> commit, but wasn't triggered as fairly big guests would be required.
> 
> Cc: qemu-stable@nongnu.org
> Reported-by: Michael S. Tsirkin <mst@redhat.com>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  hw/virtio/virtio-balloon.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> index e85d1c0d5c..515abf6553 100644
> --- a/hw/virtio/virtio-balloon.c
> +++ b/hw/virtio/virtio-balloon.c
> @@ -343,8 +343,8 @@ static void virtio_balloon_handle_output(VirtIODevice
> *vdev, VirtQueue *vq)
>          }
>  
>          while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) ==
>          4) {                                                         
> +            unsigned int p = virtio_ldl_p(vdev, &pfn);
>              hwaddr pa;
> -            int p = virtio_ldl_p(vdev, &pfn);
>  
>              pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT;
>              offset += 4;
> --
> 2.21.0

Reviewed-by: Pankaj Gupta <pagupta@redhat.com>

> 
> 
> 

[Qemu-devel] [PATCH-for-4.1 v4 2/7] virtio-balloon: Fix QEMU crashes on pagesize > BALLOON_PAGE_SIZE

[David Hildenbrand]

We are using the wrong functions to set/clear bits, effectively touching
multiple bits, writing out of range of the bitmap, resulting in memory
corruptions. We have to use set_bit()/clear_bit() instead.

Can easily be reproduced by starting a qemu guest on hugetlbfs memory,
inflating the balloon. QEMU crashes. This never could have worked
properly - especially, also pages would have been discarded when the
first sub-page would be inflated (the whole bitmap would be set).

While testing I realized, that on hugetlbfs it is pretty much impossible
to discard a page - the guest just frees the 4k sub-pages in random order
most of the time. I was only able to discard a hugepage a handful of
times - so I hope that now works correctly.

Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE <
                     host page size")
Fixes: b27b32391404 ("virtio-balloon: Fix possible guest memory corruption
                     with inflates & deflates")
Cc: qemu-stable@nongnu.org #v4.0.0
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-balloon.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 515abf6553..a78d2d2184 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -94,9 +94,8 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
         balloon->pbp->base = host_page_base;
     }
 
-    bitmap_set(balloon->pbp->bitmap,
-               (ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
-               subpages);
+    set_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
+            balloon->pbp->bitmap);
 
     if (bitmap_full(balloon->pbp->bitmap, subpages)) {
         /* We've accumulated a full host page, we can actually discard
@@ -140,9 +139,8 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
          * for a guest to do this in practice, but handle it anyway,
          * since getting it wrong could mean discarding memory the
          * guest is still using. */
-        bitmap_clear(balloon->pbp->bitmap,
-                     (ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
-                     subpages);
+        clear_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
+                  balloon->pbp->bitmap);
 
         if (bitmap_empty(balloon->pbp->bitmap, subpages)) {
             g_free(balloon->pbp);
-- 
2.21.0

[Qemu-devel] [PATCH-for-4.1 v4 3/7] virtio-balloon: Simplify deflate with pbp

[David Hildenbrand]

Let's simplify this - the case we are optimizing for is very hard to
trigger and not worth the effort. If we're switching from inflation to
deflation, let's reset the pbp.

Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-balloon.c | 26 +++++---------------------
 1 file changed, 5 insertions(+), 21 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index a78d2d2184..04a7e6c772 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -117,7 +117,7 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
     void *addr = memory_region_get_ram_ptr(mr) + offset;
     RAMBlock *rb;
     size_t rb_page_size;
-    ram_addr_t ram_offset, host_page_base;
+    ram_addr_t ram_offset;
     void *host_addr;
     int ret;
 
@@ -125,27 +125,11 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
      * host address? */
     rb = qemu_ram_block_from_host(addr, false, &ram_offset);
     rb_page_size = qemu_ram_pagesize(rb);
-    host_page_base = ram_offset & ~(rb_page_size - 1);
-
-    if (balloon->pbp
-        && rb == balloon->pbp->rb
-        && host_page_base == balloon->pbp->base) {
-        int subpages = rb_page_size / BALLOON_PAGE_SIZE;
 
-        /*
-         * This means the guest has asked to discard some of the 4kiB
-         * subpages of a host page, but then changed its mind and
-         * asked to keep them after all.  It's exceedingly unlikely
-         * for a guest to do this in practice, but handle it anyway,
-         * since getting it wrong could mean discarding memory the
-         * guest is still using. */
-        clear_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
-                  balloon->pbp->bitmap);
-
-        if (bitmap_empty(balloon->pbp->bitmap, subpages)) {
-            g_free(balloon->pbp);
-            balloon->pbp = NULL;
-        }
+    if (balloon->pbp) {
+        /* Let's play safe and always reset the pbp on deflation requests. */
+        g_free(balloon->pbp);
+        balloon->pbp = NULL;
     }
 
     host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1));
-- 
2.21.0

[Qemu-devel] [PATCH-for-4.1 v4 4/7] virtio-balloon: Better names for offset variables in inflate/deflate code

[David Hildenbrand]

"host_page_base" is really confusing, let's make this clearer, also
rename the other offsets to indicate to which base they apply.

offset -> mr_offset
ram_offset -> rb_offset
host_page_base -> rb_aligned_offset

While at it, use QEMU_ALIGN_DOWN() instead of a handcrafted computation
and move the computation to the place where it is needed.

Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-balloon.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 04a7e6c772..f206cc8bf7 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -41,24 +41,23 @@ struct PartiallyBalloonedPage {
 };
 
 static void balloon_inflate_page(VirtIOBalloon *balloon,
-                                 MemoryRegion *mr, hwaddr offset)
+                                 MemoryRegion *mr, hwaddr mr_offset)
 {
-    void *addr = memory_region_get_ram_ptr(mr) + offset;
+    void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
+    ram_addr_t rb_offset, rb_aligned_offset;
     RAMBlock *rb;
     size_t rb_page_size;
     int subpages;
-    ram_addr_t ram_offset, host_page_base;
 
     /* XXX is there a better way to get to the RAMBlock than via a
      * host address? */
-    rb = qemu_ram_block_from_host(addr, false, &ram_offset);
+    rb = qemu_ram_block_from_host(addr, false, &rb_offset);
     rb_page_size = qemu_ram_pagesize(rb);
-    host_page_base = ram_offset & ~(rb_page_size - 1);
 
     if (rb_page_size == BALLOON_PAGE_SIZE) {
         /* Easy case */
 
-        ram_block_discard_range(rb, ram_offset, rb_page_size);
+        ram_block_discard_range(rb, rb_offset, rb_page_size);
         /* We ignore errors from ram_block_discard_range(), because it
          * has already reported them, and failing to discard a balloon
          * page is not fatal */
@@ -74,11 +73,12 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
     warn_report_once(
 "Balloon used with backing page size > 4kiB, this may not be reliable");
 
+    rb_aligned_offset = QEMU_ALIGN_DOWN(rb_offset, rb_page_size);
     subpages = rb_page_size / BALLOON_PAGE_SIZE;
 
     if (balloon->pbp
         && (rb != balloon->pbp->rb
-            || host_page_base != balloon->pbp->base)) {
+            || rb_aligned_offset != balloon->pbp->base)) {
         /* We've partially ballooned part of a host page, but now
          * we're trying to balloon part of a different one.  Too hard,
          * give up on the old partial page */
@@ -91,10 +91,10 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
         size_t bitlen = BITS_TO_LONGS(subpages) * sizeof(unsigned long);
         balloon->pbp = g_malloc0(sizeof(PartiallyBalloonedPage) + bitlen);
         balloon->pbp->rb = rb;
-        balloon->pbp->base = host_page_base;
+        balloon->pbp->base = rb_aligned_offset;
     }
 
-    set_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
+    set_bit((rb_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
             balloon->pbp->bitmap);
 
     if (bitmap_full(balloon->pbp->bitmap, subpages)) {
@@ -112,18 +112,18 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
 }
 
 static void balloon_deflate_page(VirtIOBalloon *balloon,
-                                 MemoryRegion *mr, hwaddr offset)
+                                 MemoryRegion *mr, hwaddr mr_offset)
 {
-    void *addr = memory_region_get_ram_ptr(mr) + offset;
+    void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
+    ram_addr_t rb_offset;
     RAMBlock *rb;
     size_t rb_page_size;
-    ram_addr_t ram_offset;
     void *host_addr;
     int ret;
 
     /* XXX is there a better way to get to the RAMBlock than via a
      * host address? */
-    rb = qemu_ram_block_from_host(addr, false, &ram_offset);
+    rb = qemu_ram_block_from_host(addr, false, &rb_offset);
     rb_page_size = qemu_ram_pagesize(rb);
 
     if (balloon->pbp) {
-- 
2.21.0

[Qemu-devel] [PATCH-for-4.1 v4 5/7] virtio-balloon: Rework pbp tracking data

[David Hildenbrand]

Using the address of a RAMBlock to test for a matching pbp is not really
safe. Instead, let's use the guest physical address of the base page
along with the page size (via the number of subpages).

Also, let's allocate the bitmap separately. This makes the code
easier to read and maintain - we can reuse bitmap_new().

Prepare the code to move the PBP out of the device.

Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE <
                     host page size")
Fixes: b27b32391404 ("virtio-balloon: Fix possible guest memory corruption
                     with inflates & deflates")
Cc: qemu-stable@nongnu.org #v4.0.0
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-balloon.c | 69 +++++++++++++++++++++++++-------------
 1 file changed, 46 insertions(+), 23 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index f206cc8bf7..40d493a31a 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -35,16 +35,44 @@
 #define BALLOON_PAGE_SIZE  (1 << VIRTIO_BALLOON_PFN_SHIFT)
 
 struct PartiallyBalloonedPage {
-    RAMBlock *rb;
-    ram_addr_t base;
-    unsigned long bitmap[];
+    ram_addr_t base_gpa;
+    long subpages;
+    unsigned long *bitmap;
 };
 
+static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
+{
+    if (!pbp) {
+        return;
+    }
+    g_free(pbp->bitmap);
+    g_free(pbp);
+}
+
+static PartiallyBalloonedPage *virtio_balloon_pbp_alloc(ram_addr_t base_gpa,
+                                                        long subpages)
+{
+    PartiallyBalloonedPage *pbp = g_new0(PartiallyBalloonedPage, 1);
+
+    pbp->base_gpa = base_gpa;
+    pbp->subpages = subpages;
+    pbp->bitmap = bitmap_new(subpages);
+
+    return pbp;
+}
+
+static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
+                                       ram_addr_t base_gpa, long subpages)
+{
+    return pbp->subpages == subpages && pbp->base_gpa == base_gpa;
+}
+
 static void balloon_inflate_page(VirtIOBalloon *balloon,
                                  MemoryRegion *mr, hwaddr mr_offset)
 {
     void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
-    ram_addr_t rb_offset, rb_aligned_offset;
+    ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
+    PartiallyBalloonedPage **pbp = &balloon->pbp;
     RAMBlock *rb;
     size_t rb_page_size;
     int subpages;
@@ -75,39 +103,34 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
 
     rb_aligned_offset = QEMU_ALIGN_DOWN(rb_offset, rb_page_size);
     subpages = rb_page_size / BALLOON_PAGE_SIZE;
+    base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
+               (rb_offset - rb_aligned_offset);
 
-    if (balloon->pbp
-        && (rb != balloon->pbp->rb
-            || rb_aligned_offset != balloon->pbp->base)) {
+    if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa, subpages)) {
         /* We've partially ballooned part of a host page, but now
          * we're trying to balloon part of a different one.  Too hard,
          * give up on the old partial page */
-        g_free(balloon->pbp);
-        balloon->pbp = NULL;
+        virtio_balloon_pbp_free(*pbp);
+        *pbp = NULL;
     }
 
-    if (!balloon->pbp) {
-        /* Starting on a new host page */
-        size_t bitlen = BITS_TO_LONGS(subpages) * sizeof(unsigned long);
-        balloon->pbp = g_malloc0(sizeof(PartiallyBalloonedPage) + bitlen);
-        balloon->pbp->rb = rb;
-        balloon->pbp->base = rb_aligned_offset;
+    if (!*pbp) {
+        *pbp = virtio_balloon_pbp_alloc(base_gpa, subpages);
     }
 
-    set_bit((rb_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
-            balloon->pbp->bitmap);
+    set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE,
+            (*pbp)->bitmap);
 
-    if (bitmap_full(balloon->pbp->bitmap, subpages)) {
+    if (bitmap_full((*pbp)->bitmap, subpages)) {
         /* We've accumulated a full host page, we can actually discard
          * it now */
 
-        ram_block_discard_range(rb, balloon->pbp->base, rb_page_size);
+        ram_block_discard_range(rb, rb_aligned_offset, rb_page_size);
         /* We ignore errors from ram_block_discard_range(), because it
          * has already reported them, and failing to discard a balloon
          * page is not fatal */
-
-        g_free(balloon->pbp);
-        balloon->pbp = NULL;
+        virtio_balloon_pbp_free(*pbp);
+        *pbp = NULL;
     }
 }
 
@@ -128,7 +151,7 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
 
     if (balloon->pbp) {
         /* Let's play safe and always reset the pbp on deflation requests. */
-        g_free(balloon->pbp);
+        virtio_balloon_pbp_free(balloon->pbp);
         balloon->pbp = NULL;
     }
 
-- 
2.21.0

Re: [Qemu-devel] [PATCH-for-4.1 v4 5/7] virtio-balloon: Rework pbp tracking data

[David Gibson]

[-- Attachment #1: Type: text/plain, Size: 5494 bytes --]

On Thu, Jul 25, 2019 at 01:36:36PM +0200, David Hildenbrand wrote:
> Using the address of a RAMBlock to test for a matching pbp is not really
> safe. Instead, let's use the guest physical address of the base page
> along with the page size (via the number of subpages).
> 
> Also, let's allocate the bitmap separately. This makes the code
> easier to read and maintain - we can reuse bitmap_new().
> 
> Prepare the code to move the PBP out of the device.
> 
> Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE <
>                      host page size")
> Fixes: b27b32391404 ("virtio-balloon: Fix possible guest memory corruption
>                      with inflates & deflates")
> Cc: qemu-stable@nongnu.org #v4.0.0
> Signed-off-by: David Hildenbrand <david@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  hw/virtio/virtio-balloon.c | 69 +++++++++++++++++++++++++-------------
>  1 file changed, 46 insertions(+), 23 deletions(-)
> 
> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> index f206cc8bf7..40d493a31a 100644
> --- a/hw/virtio/virtio-balloon.c
> +++ b/hw/virtio/virtio-balloon.c
> @@ -35,16 +35,44 @@
>  #define BALLOON_PAGE_SIZE  (1 << VIRTIO_BALLOON_PFN_SHIFT)
>  
>  struct PartiallyBalloonedPage {
> -    RAMBlock *rb;
> -    ram_addr_t base;
> -    unsigned long bitmap[];
> +    ram_addr_t base_gpa;
> +    long subpages;
> +    unsigned long *bitmap;
>  };
>  
> +static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
> +{
> +    if (!pbp) {
> +        return;
> +    }
> +    g_free(pbp->bitmap);
> +    g_free(pbp);
> +}
> +
> +static PartiallyBalloonedPage *virtio_balloon_pbp_alloc(ram_addr_t base_gpa,
> +                                                        long subpages)
> +{
> +    PartiallyBalloonedPage *pbp = g_new0(PartiallyBalloonedPage, 1);
> +
> +    pbp->base_gpa = base_gpa;
> +    pbp->subpages = subpages;
> +    pbp->bitmap = bitmap_new(subpages);
> +
> +    return pbp;
> +}
> +
> +static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
> +                                       ram_addr_t base_gpa, long subpages)
> +{
> +    return pbp->subpages == subpages && pbp->base_gpa == base_gpa;
> +}
> +
>  static void balloon_inflate_page(VirtIOBalloon *balloon,
>                                   MemoryRegion *mr, hwaddr mr_offset)
>  {
>      void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
> -    ram_addr_t rb_offset, rb_aligned_offset;
> +    ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
> +    PartiallyBalloonedPage **pbp = &balloon->pbp;
>      RAMBlock *rb;
>      size_t rb_page_size;
>      int subpages;
> @@ -75,39 +103,34 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
>  
>      rb_aligned_offset = QEMU_ALIGN_DOWN(rb_offset, rb_page_size);
>      subpages = rb_page_size / BALLOON_PAGE_SIZE;
> +    base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
> +               (rb_offset - rb_aligned_offset);
>  
> -    if (balloon->pbp
> -        && (rb != balloon->pbp->rb
> -            || rb_aligned_offset != balloon->pbp->base)) {
> +    if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa, subpages)) {
>          /* We've partially ballooned part of a host page, but now
>           * we're trying to balloon part of a different one.  Too hard,
>           * give up on the old partial page */
> -        g_free(balloon->pbp);
> -        balloon->pbp = NULL;
> +        virtio_balloon_pbp_free(*pbp);
> +        *pbp = NULL;
>      }
>  
> -    if (!balloon->pbp) {
> -        /* Starting on a new host page */
> -        size_t bitlen = BITS_TO_LONGS(subpages) * sizeof(unsigned long);
> -        balloon->pbp = g_malloc0(sizeof(PartiallyBalloonedPage) + bitlen);
> -        balloon->pbp->rb = rb;
> -        balloon->pbp->base = rb_aligned_offset;
> +    if (!*pbp) {
> +        *pbp = virtio_balloon_pbp_alloc(base_gpa, subpages);
>      }
>  
> -    set_bit((rb_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
> -            balloon->pbp->bitmap);
> +    set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE,
> +            (*pbp)->bitmap);
>  
> -    if (bitmap_full(balloon->pbp->bitmap, subpages)) {
> +    if (bitmap_full((*pbp)->bitmap, subpages)) {
>          /* We've accumulated a full host page, we can actually discard
>           * it now */
>  
> -        ram_block_discard_range(rb, balloon->pbp->base, rb_page_size);
> +        ram_block_discard_range(rb, rb_aligned_offset, rb_page_size);
>          /* We ignore errors from ram_block_discard_range(), because it
>           * has already reported them, and failing to discard a balloon
>           * page is not fatal */
> -
> -        g_free(balloon->pbp);
> -        balloon->pbp = NULL;
> +        virtio_balloon_pbp_free(*pbp);
> +        *pbp = NULL;
>      }
>  }
>  
> @@ -128,7 +151,7 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
>  
>      if (balloon->pbp) {
>          /* Let's play safe and always reset the pbp on deflation requests. */
> -        g_free(balloon->pbp);
> +        virtio_balloon_pbp_free(balloon->pbp);
>          balloon->pbp = NULL;
>      }
>  

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

[Qemu-devel] [PATCH-for-4.1 v4 6/7] virtio-balloon: Use temporary PBP only

[David Hildenbrand]

We still have multiple issues in the current code
- The PBP is not freed during unrealize()
- The PBP is not reset on device resets: After a reset, the PBP is stale.
- We are not indicating VIRTIO_BALLOON_F_MUST_TELL_HOST, therefore
  guests (esp. legacy guests) will reuse pages without deflating,
  turning the PBP stale. Adding that would require compat handling.

Instead, let's use the PBP only temporarily, when processing one bulk of
inflation requests. This will keep guest_page_size > 4k working (with
Linux guests). There is nothing to do for deflation requests anymore.
The pbp is only used for a limited amount of time.

Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE <
                     host page size")
Cc: qemu-stable@nongnu.org #v4.0.0
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-balloon.c         | 21 +++++++++------------
 include/hw/virtio/virtio-balloon.h |  3 ---
 2 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 40d493a31a..a6282d58d4 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -34,11 +34,11 @@
 
 #define BALLOON_PAGE_SIZE  (1 << VIRTIO_BALLOON_PFN_SHIFT)
 
-struct PartiallyBalloonedPage {
+typedef struct PartiallyBalloonedPage {
     ram_addr_t base_gpa;
     long subpages;
     unsigned long *bitmap;
-};
+} PartiallyBalloonedPage;
 
 static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
 {
@@ -68,11 +68,11 @@ static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
 }
 
 static void balloon_inflate_page(VirtIOBalloon *balloon,
-                                 MemoryRegion *mr, hwaddr mr_offset)
+                                 MemoryRegion *mr, hwaddr mr_offset,
+                                 PartiallyBalloonedPage **pbp)
 {
     void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
     ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
-    PartiallyBalloonedPage **pbp = &balloon->pbp;
     RAMBlock *rb;
     size_t rb_page_size;
     int subpages;
@@ -149,12 +149,6 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
     rb = qemu_ram_block_from_host(addr, false, &rb_offset);
     rb_page_size = qemu_ram_pagesize(rb);
 
-    if (balloon->pbp) {
-        /* Let's play safe and always reset the pbp on deflation requests. */
-        virtio_balloon_pbp_free(balloon->pbp);
-        balloon->pbp = NULL;
-    }
-
     host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1));
 
     /* When a page is deflated, we hint the whole host page it lives
@@ -336,6 +330,7 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
+    PartiallyBalloonedPage *pbp = NULL;
     VirtQueueElement *elem;
     MemoryRegionSection section;
 
@@ -344,7 +339,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
         uint32_t pfn;
         elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
         if (!elem) {
-            return;
+            break;
         }
 
         while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
@@ -373,7 +368,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
             if (!qemu_balloon_is_inhibited()) {
                 if (vq == s->ivq) {
                     balloon_inflate_page(s, section.mr,
-                                         section.offset_within_region);
+                                         section.offset_within_region, &pbp);
                 } else if (vq == s->dvq) {
                     balloon_deflate_page(s, section.mr, section.offset_within_region);
                 } else {
@@ -387,6 +382,8 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
         virtio_notify(vdev, vq);
         g_free(elem);
     }
+
+    virtio_balloon_pbp_free(pbp);
 }
 
 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h
index 5a99293a45..d1c968d237 100644
--- a/include/hw/virtio/virtio-balloon.h
+++ b/include/hw/virtio/virtio-balloon.h
@@ -33,8 +33,6 @@ typedef struct virtio_balloon_stat_modern {
        uint64_t val;
 } VirtIOBalloonStatModern;
 
-typedef struct PartiallyBalloonedPage PartiallyBalloonedPage;
-
 enum virtio_balloon_free_page_report_status {
     FREE_PAGE_REPORT_S_STOP = 0,
     FREE_PAGE_REPORT_S_REQUESTED = 1,
@@ -70,7 +68,6 @@ typedef struct VirtIOBalloon {
     int64_t stats_last_update;
     int64_t stats_poll_interval;
     uint32_t host_features;
-    PartiallyBalloonedPage *pbp;
 
     bool qemu_4_0_config_size;
 } VirtIOBalloon;
-- 
2.21.0

Re: [Qemu-devel] [PATCH-for-4.1 v4 6/7] virtio-balloon: Use temporary PBP only

[Michael S. Tsirkin]

On Thu, Jul 25, 2019 at 01:36:37PM +0200, David Hildenbrand wrote:
> We still have multiple issues in the current code
> - The PBP is not freed during unrealize()
> - The PBP is not reset on device resets: After a reset, the PBP is stale.
> - We are not indicating VIRTIO_BALLOON_F_MUST_TELL_HOST, therefore
>   guests (esp. legacy guests) will reuse pages without deflating,
>   turning the PBP stale. Adding that would require compat handling.
> 
> Instead, let's use the PBP only temporarily, when processing one bulk of
> inflation requests. This will keep guest_page_size > 4k working (with
> Linux guests). There is nothing to do for deflation requests anymore.
> The pbp is only used for a limited amount of time.
> 
> Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE <
>                      host page size")
> Cc: qemu-stable@nongnu.org #v4.0.0
> Suggested-by: Michael S. Tsirkin <mst@redhat.com>
> Acked-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  hw/virtio/virtio-balloon.c         | 21 +++++++++------------
>  include/hw/virtio/virtio-balloon.h |  3 ---
>  2 files changed, 9 insertions(+), 15 deletions(-)
> 
> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> index 40d493a31a..a6282d58d4 100644
> --- a/hw/virtio/virtio-balloon.c
> +++ b/hw/virtio/virtio-balloon.c
> @@ -34,11 +34,11 @@
>  
>  #define BALLOON_PAGE_SIZE  (1 << VIRTIO_BALLOON_PFN_SHIFT)
>  
> -struct PartiallyBalloonedPage {
> +typedef struct PartiallyBalloonedPage {
>      ram_addr_t base_gpa;
>      long subpages;
>      unsigned long *bitmap;
> -};
> +} PartiallyBalloonedPage;
>  
>  static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
>  {
> @@ -68,11 +68,11 @@ static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
>  }
>  
>  static void balloon_inflate_page(VirtIOBalloon *balloon,
> -                                 MemoryRegion *mr, hwaddr mr_offset)
> +                                 MemoryRegion *mr, hwaddr mr_offset,
> +                                 PartiallyBalloonedPage **pbp)
>  {
>      void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
>      ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
> -    PartiallyBalloonedPage **pbp = &balloon->pbp;
>      RAMBlock *rb;
>      size_t rb_page_size;
>      int subpages;
> @@ -149,12 +149,6 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
>      rb = qemu_ram_block_from_host(addr, false, &rb_offset);
>      rb_page_size = qemu_ram_pagesize(rb);
>  
> -    if (balloon->pbp) {
> -        /* Let's play safe and always reset the pbp on deflation requests. */
> -        virtio_balloon_pbp_free(balloon->pbp);
> -        balloon->pbp = NULL;
> -    }
> -
>      host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1));
>  
>      /* When a page is deflated, we hint the whole host page it lives
> @@ -336,6 +330,7 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
>  static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>  {
>      VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
> +    PartiallyBalloonedPage *pbp = NULL;
>      VirtQueueElement *elem;
>      MemoryRegionSection section;
>  
> @@ -344,7 +339,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>          uint32_t pfn;
>          elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
>          if (!elem) {
> -            return;
> +            break;
>          }
>  
>          while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
> @@ -373,7 +368,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>              if (!qemu_balloon_is_inhibited()) {
>                  if (vq == s->ivq) {
>                      balloon_inflate_page(s, section.mr,
> -                                         section.offset_within_region);
> +                                         section.offset_within_region, &pbp);
>                  } else if (vq == s->dvq) {
>                      balloon_deflate_page(s, section.mr, section.offset_within_region);
>                  } else {
> @@ -387,6 +382,8 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>          virtio_notify(vdev, vq);
>          g_free(elem);
>      }
> +
> +    virtio_balloon_pbp_free(pbp);
>  }
>  
>  static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)

Oops this is not early enough.
We must not track pbp across elements: once we push an element
guest can reuse the page.

I propose changing virtio_balloon_pbp_free to get
PartiallyBalloonedPage** and set it to NULL.

Call that within the loop after g_free(elem);




> diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h
> index 5a99293a45..d1c968d237 100644
> --- a/include/hw/virtio/virtio-balloon.h
> +++ b/include/hw/virtio/virtio-balloon.h
> @@ -33,8 +33,6 @@ typedef struct virtio_balloon_stat_modern {
>         uint64_t val;
>  } VirtIOBalloonStatModern;
>  
> -typedef struct PartiallyBalloonedPage PartiallyBalloonedPage;
> -
>  enum virtio_balloon_free_page_report_status {
>      FREE_PAGE_REPORT_S_STOP = 0,
>      FREE_PAGE_REPORT_S_REQUESTED = 1,
> @@ -70,7 +68,6 @@ typedef struct VirtIOBalloon {
>      int64_t stats_last_update;
>      int64_t stats_poll_interval;
>      uint32_t host_features;
> -    PartiallyBalloonedPage *pbp;
>  
>      bool qemu_4_0_config_size;
>  } VirtIOBalloon;
> -- 
> 2.21.0

Re: [Qemu-devel] [PATCH-for-4.1 v4 6/7] virtio-balloon: Use temporary PBP only

[David Hildenbrand]

On 25.07.19 13:53, Michael S. Tsirkin wrote:
> On Thu, Jul 25, 2019 at 01:36:37PM +0200, David Hildenbrand wrote:
>> We still have multiple issues in the current code
>> - The PBP is not freed during unrealize()
>> - The PBP is not reset on device resets: After a reset, the PBP is stale.
>> - We are not indicating VIRTIO_BALLOON_F_MUST_TELL_HOST, therefore
>>   guests (esp. legacy guests) will reuse pages without deflating,
>>   turning the PBP stale. Adding that would require compat handling.
>>
>> Instead, let's use the PBP only temporarily, when processing one bulk of
>> inflation requests. This will keep guest_page_size > 4k working (with
>> Linux guests). There is nothing to do for deflation requests anymore.
>> The pbp is only used for a limited amount of time.
>>
>> Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE <
>>                      host page size")
>> Cc: qemu-stable@nongnu.org #v4.0.0
>> Suggested-by: Michael S. Tsirkin <mst@redhat.com>
>> Acked-by: David Gibson <david@gibson.dropbear.id.au>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
>> ---
>>  hw/virtio/virtio-balloon.c         | 21 +++++++++------------
>>  include/hw/virtio/virtio-balloon.h |  3 ---
>>  2 files changed, 9 insertions(+), 15 deletions(-)
>>
>> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
>> index 40d493a31a..a6282d58d4 100644
>> --- a/hw/virtio/virtio-balloon.c
>> +++ b/hw/virtio/virtio-balloon.c
>> @@ -34,11 +34,11 @@
>>  
>>  #define BALLOON_PAGE_SIZE  (1 << VIRTIO_BALLOON_PFN_SHIFT)
>>  
>> -struct PartiallyBalloonedPage {
>> +typedef struct PartiallyBalloonedPage {
>>      ram_addr_t base_gpa;
>>      long subpages;
>>      unsigned long *bitmap;
>> -};
>> +} PartiallyBalloonedPage;
>>  
>>  static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
>>  {
>> @@ -68,11 +68,11 @@ static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
>>  }
>>  
>>  static void balloon_inflate_page(VirtIOBalloon *balloon,
>> -                                 MemoryRegion *mr, hwaddr mr_offset)
>> +                                 MemoryRegion *mr, hwaddr mr_offset,
>> +                                 PartiallyBalloonedPage **pbp)
>>  {
>>      void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
>>      ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
>> -    PartiallyBalloonedPage **pbp = &balloon->pbp;
>>      RAMBlock *rb;
>>      size_t rb_page_size;
>>      int subpages;
>> @@ -149,12 +149,6 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
>>      rb = qemu_ram_block_from_host(addr, false, &rb_offset);
>>      rb_page_size = qemu_ram_pagesize(rb);
>>  
>> -    if (balloon->pbp) {
>> -        /* Let's play safe and always reset the pbp on deflation requests. */
>> -        virtio_balloon_pbp_free(balloon->pbp);
>> -        balloon->pbp = NULL;
>> -    }
>> -
>>      host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1));
>>  
>>      /* When a page is deflated, we hint the whole host page it lives
>> @@ -336,6 +330,7 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
>>  static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>>  {
>>      VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
>> +    PartiallyBalloonedPage *pbp = NULL;
>>      VirtQueueElement *elem;
>>      MemoryRegionSection section;
>>  
>> @@ -344,7 +339,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>>          uint32_t pfn;
>>          elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
>>          if (!elem) {
>> -            return;
>> +            break;
>>          }
>>  
>>          while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
>> @@ -373,7 +368,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>>              if (!qemu_balloon_is_inhibited()) {
>>                  if (vq == s->ivq) {
>>                      balloon_inflate_page(s, section.mr,
>> -                                         section.offset_within_region);
>> +                                         section.offset_within_region, &pbp);
>>                  } else if (vq == s->dvq) {
>>                      balloon_deflate_page(s, section.mr, section.offset_within_region);
>>                  } else {
>> @@ -387,6 +382,8 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>>          virtio_notify(vdev, vq);
>>          g_free(elem);
>>      }
>> +
>> +    virtio_balloon_pbp_free(pbp);
>>  }
>>  
>>  static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
> 
> Oops this is not early enough.
> We must not track pbp across elements: once we push an element
> guest can reuse the page.
> 

Right, it has to go into the loop.

-- 

Thanks,

David / dhildenb

[Qemu-devel] [PATCH-for-4.1 v4 7/7] virtio-balloon: No need to track subpages for the PBP anymore

[David Hildenbrand]

As ramblocks cannot get removed/readded while we are processing a bulk
of inflation requests, there is no more need to track the page size
in form of the number of subpages.

Suggested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-balloon.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index a6282d58d4..fe9664e42c 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -36,7 +36,6 @@
 
 typedef struct PartiallyBalloonedPage {
     ram_addr_t base_gpa;
-    long subpages;
     unsigned long *bitmap;
 } PartiallyBalloonedPage;
 
@@ -55,16 +54,15 @@ static PartiallyBalloonedPage *virtio_balloon_pbp_alloc(ram_addr_t base_gpa,
     PartiallyBalloonedPage *pbp = g_new0(PartiallyBalloonedPage, 1);
 
     pbp->base_gpa = base_gpa;
-    pbp->subpages = subpages;
     pbp->bitmap = bitmap_new(subpages);
 
     return pbp;
 }
 
 static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
-                                       ram_addr_t base_gpa, long subpages)
+                                       ram_addr_t base_gpa)
 {
-    return pbp->subpages == subpages && pbp->base_gpa == base_gpa;
+    return pbp->base_gpa == base_gpa;
 }
 
 static void balloon_inflate_page(VirtIOBalloon *balloon,
@@ -106,7 +104,7 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
     base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
                (rb_offset - rb_aligned_offset);
 
-    if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa, subpages)) {
+    if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa)) {
         /* We've partially ballooned part of a host page, but now
          * we're trying to balloon part of a different one.  Too hard,
          * give up on the old partial page */
-- 
2.21.0

[Qemu-devel] [PULL 11/12] virtio-balloon: don't track subpages for the PBP

[Michael S. Tsirkin]

From: David Hildenbrand <david@redhat.com>

As ramblocks cannot get removed/readded while we are processing a bulk
of inflation requests, there is no more need to track the page size
in form of the number of subpages.

Suggested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20190725113638.4702-8-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/virtio/virtio-balloon.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index a6282d58d4..fe9664e42c 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -36,7 +36,6 @@
 
 typedef struct PartiallyBalloonedPage {
     ram_addr_t base_gpa;
-    long subpages;
     unsigned long *bitmap;
 } PartiallyBalloonedPage;
 
@@ -55,16 +54,15 @@ static PartiallyBalloonedPage *virtio_balloon_pbp_alloc(ram_addr_t base_gpa,
     PartiallyBalloonedPage *pbp = g_new0(PartiallyBalloonedPage, 1);
 
     pbp->base_gpa = base_gpa;
-    pbp->subpages = subpages;
     pbp->bitmap = bitmap_new(subpages);
 
     return pbp;
 }
 
 static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
-                                       ram_addr_t base_gpa, long subpages)
+                                       ram_addr_t base_gpa)
 {
-    return pbp->subpages == subpages && pbp->base_gpa == base_gpa;
+    return pbp->base_gpa == base_gpa;
 }
 
 static void balloon_inflate_page(VirtIOBalloon *balloon,
@@ -106,7 +104,7 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
     base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
                (rb_offset - rb_aligned_offset);
 
-    if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa, subpages)) {
+    if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa)) {
         /* We've partially ballooned part of a host page, but now
          * we're trying to balloon part of a different one.  Too hard,
          * give up on the old partial page */
-- 
MST

Re: [Qemu-devel] [PATCH-for-4.1 v4 7/7] virtio-balloon: No need to track subpages for the PBP anymore

[David Gibson]

[-- Attachment #1: Type: text/plain, Size: 2377 bytes --]

On Thu, Jul 25, 2019 at 01:36:38PM +0200, David Hildenbrand wrote:
> As ramblocks cannot get removed/readded while we are processing a bulk
> of inflation requests, there is no more need to track the page size
> in form of the number of subpages.
> 
> Suggested-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  hw/virtio/virtio-balloon.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> index a6282d58d4..fe9664e42c 100644
> --- a/hw/virtio/virtio-balloon.c
> +++ b/hw/virtio/virtio-balloon.c
> @@ -36,7 +36,6 @@
>  
>  typedef struct PartiallyBalloonedPage {
>      ram_addr_t base_gpa;
> -    long subpages;
>      unsigned long *bitmap;
>  } PartiallyBalloonedPage;
>  
> @@ -55,16 +54,15 @@ static PartiallyBalloonedPage *virtio_balloon_pbp_alloc(ram_addr_t base_gpa,
>      PartiallyBalloonedPage *pbp = g_new0(PartiallyBalloonedPage, 1);
>  
>      pbp->base_gpa = base_gpa;
> -    pbp->subpages = subpages;
>      pbp->bitmap = bitmap_new(subpages);
>  
>      return pbp;
>  }
>  
>  static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
> -                                       ram_addr_t base_gpa, long subpages)
> +                                       ram_addr_t base_gpa)
>  {
> -    return pbp->subpages == subpages && pbp->base_gpa == base_gpa;
> +    return pbp->base_gpa == base_gpa;
>  }
>  
>  static void balloon_inflate_page(VirtIOBalloon *balloon,
> @@ -106,7 +104,7 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
>      base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
>                 (rb_offset - rb_aligned_offset);
>  
> -    if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa, subpages)) {
> +    if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa)) {
>          /* We've partially ballooned part of a host page, but now
>           * we're trying to balloon part of a different one.  Too hard,
>           * give up on the old partial page */

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

[Qemu-devel] [PULL 00/12] virtio, pc: fixes, cleanups

[Michael S. Tsirkin]

The following changes since commit bf8b024372bf8abf5a9f40bfa65eeefad23ff988:

  Update version for v4.1.0-rc2 release (2019-07-23 18:28:08 +0100)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/virt/kvm/mst/qemu.git tags/for_upstream

for you to fetch changes up to 1b47b37c33ec01ae1efc527f4c97f97f93723bc4:

  virtio-balloon: free pbp more aggressively (2019-07-25 11:19:25 -0400)

----------------------------------------------------------------
virtio, pc: fixes, cleanups

A bunch of fixes all over the place.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

----------------------------------------------------------------
David Hildenbrand (7):
      virtio-balloon: Fix wrong sign extension of PFNs
      virtio-balloon: Fix QEMU crashes on pagesize > BALLOON_PAGE_SIZE
      virtio-balloon: Simplify deflate with pbp
      virtio-balloon: Better names for offset variables in inflate/deflate code
      virtio-balloon: Rework pbp tracking data
      virtio-balloon: Use temporary PBP only
      virtio-balloon: don't track subpages for the PBP

Evgeny Yakovlev (2):
      i386/acpi: fix gint overflow in crs_range_compare
      i386/acpi: show PCI Express bus on pxb-pcie expanders

Jan Kiszka (1):
      ioapic: kvm: Skip route updates for masked pins

Michael S. Tsirkin (1):
      virtio-balloon: free pbp more aggressively

Stefan Hajnoczi (1):
      docs: clarify multiqueue vs multiple virtqueues

 include/hw/virtio/virtio-balloon.h |   3 -
 hw/i386/acpi-build.c               |  17 ++++--
 hw/intc/ioapic.c                   |   8 ++-
 hw/virtio/virtio-balloon.c         | 115 ++++++++++++++++++-------------------
 docs/interop/vhost-user.rst        |  17 ++++++
 5 files changed, 90 insertions(+), 70 deletions(-)

[Qemu-devel] [PULL 12/12] virtio-balloon: free pbp more aggressively

[Michael S. Tsirkin]

Previous patches switched to a temporary pbp but that does not go far
enough: after device uses a buffer, guest is free to reuse it, so
tracking the page and freeing it later is wrong.

Free and reset the pbp after we push each element.

Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE < host page size")
Cc: qemu-stable@nongnu.org #v4.0.0
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/virtio/virtio-balloon.c | 37 ++++++++++++++++---------------------
 1 file changed, 16 insertions(+), 21 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index fe9664e42c..25de154307 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -41,22 +41,19 @@ typedef struct PartiallyBalloonedPage {
 
 static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
 {
-    if (!pbp) {
+    if (!pbp->bitmap) {
         return;
     }
     g_free(pbp->bitmap);
-    g_free(pbp);
+    pbp->bitmap = NULL;
 }
 
-static PartiallyBalloonedPage *virtio_balloon_pbp_alloc(ram_addr_t base_gpa,
-                                                        long subpages)
+static void virtio_balloon_pbp_alloc(PartiallyBalloonedPage *pbp,
+                                     ram_addr_t base_gpa,
+                                     long subpages)
 {
-    PartiallyBalloonedPage *pbp = g_new0(PartiallyBalloonedPage, 1);
-
     pbp->base_gpa = base_gpa;
     pbp->bitmap = bitmap_new(subpages);
-
-    return pbp;
 }
 
 static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
@@ -67,7 +64,7 @@ static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
 
 static void balloon_inflate_page(VirtIOBalloon *balloon,
                                  MemoryRegion *mr, hwaddr mr_offset,
-                                 PartiallyBalloonedPage **pbp)
+                                 PartiallyBalloonedPage *pbp)
 {
     void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
     ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
@@ -104,22 +101,21 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
     base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
                (rb_offset - rb_aligned_offset);
 
-    if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa)) {
+    if (pbp->bitmap && !virtio_balloon_pbp_matches(pbp, base_gpa)) {
         /* We've partially ballooned part of a host page, but now
          * we're trying to balloon part of a different one.  Too hard,
          * give up on the old partial page */
-        virtio_balloon_pbp_free(*pbp);
-        *pbp = NULL;
+        virtio_balloon_pbp_free(pbp);
     }
 
-    if (!*pbp) {
-        *pbp = virtio_balloon_pbp_alloc(base_gpa, subpages);
+    if (!pbp->bitmap) {
+        virtio_balloon_pbp_alloc(pbp, base_gpa, subpages);
     }
 
     set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE,
-            (*pbp)->bitmap);
+            pbp->bitmap);
 
-    if (bitmap_full((*pbp)->bitmap, subpages)) {
+    if (bitmap_full(pbp->bitmap, subpages)) {
         /* We've accumulated a full host page, we can actually discard
          * it now */
 
@@ -127,8 +123,7 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
         /* We ignore errors from ram_block_discard_range(), because it
          * has already reported them, and failing to discard a balloon
          * page is not fatal */
-        virtio_balloon_pbp_free(*pbp);
-        *pbp = NULL;
+        virtio_balloon_pbp_free(pbp);
     }
 }
 
@@ -328,13 +323,14 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
-    PartiallyBalloonedPage *pbp = NULL;
     VirtQueueElement *elem;
     MemoryRegionSection section;
 
     for (;;) {
+        PartiallyBalloonedPage pbp = {};
         size_t offset = 0;
         uint32_t pfn;
+
         elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
         if (!elem) {
             break;
@@ -379,9 +375,8 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
         virtqueue_push(vq, elem, offset);
         virtio_notify(vdev, vq);
         g_free(elem);
+        virtio_balloon_pbp_free(&pbp);
     }
-
-    virtio_balloon_pbp_free(pbp);
 }
 
 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
-- 
MST

Re: [Qemu-devel] [PULL 00/12] virtio, pc: fixes, cleanups

[Peter Maydell]

On Thu, 25 Jul 2019 at 16:31, Michael S. Tsirkin <mst@redhat.com> wrote:
>
> The following changes since commit bf8b024372bf8abf5a9f40bfa65eeefad23ff988:
>
>   Update version for v4.1.0-rc2 release (2019-07-23 18:28:08 +0100)
>
> are available in the Git repository at:
>
>   git://git.kernel.org/pub/scm/virt/kvm/mst/qemu.git tags/for_upstream
>
> for you to fetch changes up to 1b47b37c33ec01ae1efc527f4c97f97f93723bc4:
>
>   virtio-balloon: free pbp more aggressively (2019-07-25 11:19:25 -0400)
>
> ----------------------------------------------------------------
> virtio, pc: fixes, cleanups
>
> A bunch of fixes all over the place.
>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>


Applied, thanks.

Please update the changelog at https://wiki.qemu.org/ChangeLog/4.1
for any user-visible changes.

-- PMM

[Qemu-devel] [PATCH-for-4.1 v3 0/6] virtio-balloon: fixes

[David Hildenbrand]

As we discovered yet another issue with current PBP code, we decided
to use a local PBP only, limited to one series of inflation requests.
This series supersedes:
- [PATCH-for-4.1 v2 0/3] virtio-balloon: fixes for PartialBalloonedPage
- [PATCH v1 0/3] virtio-balloon: PartialBalloonedPage rework

Patch #1 is a fix for a wrong sign extension (MST brought this up but
wasn't sure if it is broen - I think it is indeed broken). Patch #2 fixed
QEMU segfaults. Patch #3 and #4 are cleanups that make follow-up fixes
easier. Patch #5 avoids using RAMBlock addresses as tokens and patch #6
fixes all kinds of issues related to using a global PBP.

We want to have all patches in 4.1 and backport them to 4.0. Patch #1
needs backports to basically all QEMU releases with virtio-balloon.

Did a quick sanity test, hopefully no other BUG sneeked in. Will do some
more testing.

Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: qemu-stable@nongnu.org

David Hildenbrand (6):
  virtio-balloon: Fix wrong sign extension of PFNs
  virtio-balloon: Fix QEMU crashes on pagesize > BALLOON_PAGE_SIZE
  virtio-balloon: Simplify deflate with pbp
  virtio-balloon: Better names for offset variables in inflate/deflate
    code
  virtio-balloon: Rework pbp tracking data
  virtio-balloon: Use temporary PBP only

 hw/virtio/virtio-balloon.c         | 122 +++++++++++++++--------------
 include/hw/virtio/virtio-balloon.h |   3 -
 2 files changed, 62 insertions(+), 63 deletions(-)

-- 
2.21.0

[Qemu-devel] [PATCH-for-4.1 v3 1/6] virtio-balloon: Fix wrong sign extension of PFNs

[David Hildenbrand]

If we directly cast from int to uint64_t, we will first sign-extend to
an int64_t, which is wrong. We actually want to treat the PFNs like
unsigned values.

As far as I can see, this dates back to the initial virtio-balloon
commit, but wasn't triggered as fairly big guests would be required.

Cc: qemu-stable@nongnu.org
Reported-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-balloon.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index e85d1c0d5c..515abf6553 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -343,8 +343,8 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
         }
 
         while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
+            unsigned int p = virtio_ldl_p(vdev, &pfn);
             hwaddr pa;
-            int p = virtio_ldl_p(vdev, &pfn);
 
             pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT;
             offset += 4;
-- 
2.21.0

[Qemu-devel] [PULL 05/12] virtio-balloon: Fix wrong sign extension of PFNs

[Michael S. Tsirkin]

From: David Hildenbrand <david@redhat.com>

If we directly cast from int to uint64_t, we will first sign-extend to
an int64_t, which is wrong. We actually want to treat the PFNs like
unsigned values.

As far as I can see, this dates back to the initial virtio-balloon
commit, but wasn't triggered as fairly big guests would be required.

Cc: qemu-stable@nongnu.org
Reported-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20190722134108.22151-2-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/virtio/virtio-balloon.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index e85d1c0d5c..515abf6553 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -343,8 +343,8 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
         }
 
         while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
+            unsigned int p = virtio_ldl_p(vdev, &pfn);
             hwaddr pa;
-            int p = virtio_ldl_p(vdev, &pfn);
 
             pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT;
             offset += 4;
-- 
MST

Re: [Qemu-devel] [PATCH-for-4.1 v3 1/6] virtio-balloon: Fix wrong sign extension of PFNs

[David Gibson]

[-- Attachment #1: Type: text/plain, Size: 1492 bytes --]

On Mon, Jul 22, 2019 at 03:41:03PM +0200, David Hildenbrand wrote:
> If we directly cast from int to uint64_t, we will first sign-extend to
> an int64_t, which is wrong. We actually want to treat the PFNs like
> unsigned values.
> 
> As far as I can see, this dates back to the initial virtio-balloon
> commit, but wasn't triggered as fairly big guests would be required.
> 
> Cc: qemu-stable@nongnu.org
> Reported-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  hw/virtio/virtio-balloon.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> index e85d1c0d5c..515abf6553 100644
> --- a/hw/virtio/virtio-balloon.c
> +++ b/hw/virtio/virtio-balloon.c
> @@ -343,8 +343,8 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>          }
>  
>          while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
> +            unsigned int p = virtio_ldl_p(vdev, &pfn);
>              hwaddr pa;
> -            int p = virtio_ldl_p(vdev, &pfn);
>  
>              pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT;
>              offset += 4;

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

[Qemu-devel] [PATCH-for-4.1 v3 2/6] virtio-balloon: Fix QEMU crashes on pagesize > BALLOON_PAGE_SIZE

[David Hildenbrand]

We are using the wrong functions to set/clear bits, effectively touching
multiple bits, writing out of range of the bitmap, resulting in memory
corruptions. We have to use set_bit()/clear_bit() instead.

Can easily be reproduced by starting a qemu guest on hugetlbfs memory,
inflating the balloon. QEMU crashes. This never could have worked
properly - especially, also pages would have been discarded when the
first sub-page would be inflated (the whole bitmap would be set).

While testing I realized, that on hugetlbfs it is pretty much impossible
to discard a page - the guest just frees the 4k sub-pages in random order
most of the time. I was only able to discard a hugepage a handful of
times - so I hope that now works correctly.

Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE <
                     host page size")
Fixes: b27b32391404 ("virtio-balloon: Fix possible guest memory corruption
                     with inflates & deflates")
Cc: qemu-stable@nongnu.org #v4.0.0
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-balloon.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 515abf6553..a78d2d2184 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -94,9 +94,8 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
         balloon->pbp->base = host_page_base;
     }
 
-    bitmap_set(balloon->pbp->bitmap,
-               (ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
-               subpages);
+    set_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
+            balloon->pbp->bitmap);
 
     if (bitmap_full(balloon->pbp->bitmap, subpages)) {
         /* We've accumulated a full host page, we can actually discard
@@ -140,9 +139,8 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
          * for a guest to do this in practice, but handle it anyway,
          * since getting it wrong could mean discarding memory the
          * guest is still using. */
-        bitmap_clear(balloon->pbp->bitmap,
-                     (ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
-                     subpages);
+        clear_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
+                  balloon->pbp->bitmap);
 
         if (bitmap_empty(balloon->pbp->bitmap, subpages)) {
             g_free(balloon->pbp);
-- 
2.21.0

[Qemu-devel] [PULL 06/12] virtio-balloon: Fix QEMU crashes on pagesize > BALLOON_PAGE_SIZE

[Michael S. Tsirkin]

From: David Hildenbrand <david@redhat.com>

We are using the wrong functions to set/clear bits, effectively touching
multiple bits, writing out of range of the bitmap, resulting in memory
corruptions. We have to use set_bit()/clear_bit() instead.

Can easily be reproduced by starting a qemu guest on hugetlbfs memory,
inflating the balloon. QEMU crashes. This never could have worked
properly - especially, also pages would have been discarded when the
first sub-page would be inflated (the whole bitmap would be set).

While testing I realized, that on hugetlbfs it is pretty much impossible
to discard a page - the guest just frees the 4k sub-pages in random order
most of the time. I was only able to discard a hugepage a handful of
times - so I hope that now works correctly.

Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE < host page size")
Fixes: b27b32391404 ("virtio-balloon: Fix possible guest memory corruption with inflates & deflates")
Cc: qemu-stable@nongnu.org #v4.0.0
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20190722134108.22151-3-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/virtio/virtio-balloon.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 515abf6553..a78d2d2184 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -94,9 +94,8 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
         balloon->pbp->base = host_page_base;
     }
 
-    bitmap_set(balloon->pbp->bitmap,
-               (ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
-               subpages);
+    set_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
+            balloon->pbp->bitmap);
 
     if (bitmap_full(balloon->pbp->bitmap, subpages)) {
         /* We've accumulated a full host page, we can actually discard
@@ -140,9 +139,8 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
          * for a guest to do this in practice, but handle it anyway,
          * since getting it wrong could mean discarding memory the
          * guest is still using. */
-        bitmap_clear(balloon->pbp->bitmap,
-                     (ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
-                     subpages);
+        clear_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
+                  balloon->pbp->bitmap);
 
         if (bitmap_empty(balloon->pbp->bitmap, subpages)) {
             g_free(balloon->pbp);
-- 
MST

[Qemu-devel] [PATCH-for-4.1 v3 3/6] virtio-balloon: Simplify deflate with pbp

[David Hildenbrand]

Let's simplify this - the case we are optimizing for is very hard to
trigger and not worth the effort. If we're switching from inflation to
deflation, let's reset the pbp.

Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-balloon.c | 26 +++++---------------------
 1 file changed, 5 insertions(+), 21 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index a78d2d2184..04a7e6c772 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -117,7 +117,7 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
     void *addr = memory_region_get_ram_ptr(mr) + offset;
     RAMBlock *rb;
     size_t rb_page_size;
-    ram_addr_t ram_offset, host_page_base;
+    ram_addr_t ram_offset;
     void *host_addr;
     int ret;
 
@@ -125,27 +125,11 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
      * host address? */
     rb = qemu_ram_block_from_host(addr, false, &ram_offset);
     rb_page_size = qemu_ram_pagesize(rb);
-    host_page_base = ram_offset & ~(rb_page_size - 1);
-
-    if (balloon->pbp
-        && rb == balloon->pbp->rb
-        && host_page_base == balloon->pbp->base) {
-        int subpages = rb_page_size / BALLOON_PAGE_SIZE;
 
-        /*
-         * This means the guest has asked to discard some of the 4kiB
-         * subpages of a host page, but then changed its mind and
-         * asked to keep them after all.  It's exceedingly unlikely
-         * for a guest to do this in practice, but handle it anyway,
-         * since getting it wrong could mean discarding memory the
-         * guest is still using. */
-        clear_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
-                  balloon->pbp->bitmap);
-
-        if (bitmap_empty(balloon->pbp->bitmap, subpages)) {
-            g_free(balloon->pbp);
-            balloon->pbp = NULL;
-        }
+    if (balloon->pbp) {
+        /* Let's play safe and always reset the pbp on deflation requests. */
+        g_free(balloon->pbp);
+        balloon->pbp = NULL;
     }
 
     host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1));
-- 
2.21.0

[Qemu-devel] [PULL 07/12] virtio-balloon: Simplify deflate with pbp

[Michael S. Tsirkin]

From: David Hildenbrand <david@redhat.com>

Let's simplify this - the case we are optimizing for is very hard to
trigger and not worth the effort. If we're switching from inflation to
deflation, let's reset the pbp.

Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20190722134108.22151-4-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/virtio/virtio-balloon.c | 26 +++++---------------------
 1 file changed, 5 insertions(+), 21 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index a78d2d2184..04a7e6c772 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -117,7 +117,7 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
     void *addr = memory_region_get_ram_ptr(mr) + offset;
     RAMBlock *rb;
     size_t rb_page_size;
-    ram_addr_t ram_offset, host_page_base;
+    ram_addr_t ram_offset;
     void *host_addr;
     int ret;
 
@@ -125,27 +125,11 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
      * host address? */
     rb = qemu_ram_block_from_host(addr, false, &ram_offset);
     rb_page_size = qemu_ram_pagesize(rb);
-    host_page_base = ram_offset & ~(rb_page_size - 1);
-
-    if (balloon->pbp
-        && rb == balloon->pbp->rb
-        && host_page_base == balloon->pbp->base) {
-        int subpages = rb_page_size / BALLOON_PAGE_SIZE;
 
-        /*
-         * This means the guest has asked to discard some of the 4kiB
-         * subpages of a host page, but then changed its mind and
-         * asked to keep them after all.  It's exceedingly unlikely
-         * for a guest to do this in practice, but handle it anyway,
-         * since getting it wrong could mean discarding memory the
-         * guest is still using. */
-        clear_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
-                  balloon->pbp->bitmap);
-
-        if (bitmap_empty(balloon->pbp->bitmap, subpages)) {
-            g_free(balloon->pbp);
-            balloon->pbp = NULL;
-        }
+    if (balloon->pbp) {
+        /* Let's play safe and always reset the pbp on deflation requests. */
+        g_free(balloon->pbp);
+        balloon->pbp = NULL;
     }
 
     host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1));
-- 
MST

[Qemu-devel] [PATCH-for-4.1 v3 4/6] virtio-balloon: Better names for offset variables in inflate/deflate code

[David Hildenbrand]

"host_page_base" is really confusing, let's make this clearer, also
rename the other offsets to indicate to which base they apply.

offset -> mr_offset
ram_offset -> rb_offset
host_page_base -> rb_aligned_offset

While at it, use QEMU_ALIGN_DOWN() instead of a handcrafted computation
and move the computation to the place where it is needed.

Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-balloon.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 04a7e6c772..f206cc8bf7 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -41,24 +41,23 @@ struct PartiallyBalloonedPage {
 };
 
 static void balloon_inflate_page(VirtIOBalloon *balloon,
-                                 MemoryRegion *mr, hwaddr offset)
+                                 MemoryRegion *mr, hwaddr mr_offset)
 {
-    void *addr = memory_region_get_ram_ptr(mr) + offset;
+    void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
+    ram_addr_t rb_offset, rb_aligned_offset;
     RAMBlock *rb;
     size_t rb_page_size;
     int subpages;
-    ram_addr_t ram_offset, host_page_base;
 
     /* XXX is there a better way to get to the RAMBlock than via a
      * host address? */
-    rb = qemu_ram_block_from_host(addr, false, &ram_offset);
+    rb = qemu_ram_block_from_host(addr, false, &rb_offset);
     rb_page_size = qemu_ram_pagesize(rb);
-    host_page_base = ram_offset & ~(rb_page_size - 1);
 
     if (rb_page_size == BALLOON_PAGE_SIZE) {
         /* Easy case */
 
-        ram_block_discard_range(rb, ram_offset, rb_page_size);
+        ram_block_discard_range(rb, rb_offset, rb_page_size);
         /* We ignore errors from ram_block_discard_range(), because it
          * has already reported them, and failing to discard a balloon
          * page is not fatal */
@@ -74,11 +73,12 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
     warn_report_once(
 "Balloon used with backing page size > 4kiB, this may not be reliable");
 
+    rb_aligned_offset = QEMU_ALIGN_DOWN(rb_offset, rb_page_size);
     subpages = rb_page_size / BALLOON_PAGE_SIZE;
 
     if (balloon->pbp
         && (rb != balloon->pbp->rb
-            || host_page_base != balloon->pbp->base)) {
+            || rb_aligned_offset != balloon->pbp->base)) {
         /* We've partially ballooned part of a host page, but now
          * we're trying to balloon part of a different one.  Too hard,
          * give up on the old partial page */
@@ -91,10 +91,10 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
         size_t bitlen = BITS_TO_LONGS(subpages) * sizeof(unsigned long);
         balloon->pbp = g_malloc0(sizeof(PartiallyBalloonedPage) + bitlen);
         balloon->pbp->rb = rb;
-        balloon->pbp->base = host_page_base;
+        balloon->pbp->base = rb_aligned_offset;
     }
 
-    set_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
+    set_bit((rb_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
             balloon->pbp->bitmap);
 
     if (bitmap_full(balloon->pbp->bitmap, subpages)) {
@@ -112,18 +112,18 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
 }
 
 static void balloon_deflate_page(VirtIOBalloon *balloon,
-                                 MemoryRegion *mr, hwaddr offset)
+                                 MemoryRegion *mr, hwaddr mr_offset)
 {
-    void *addr = memory_region_get_ram_ptr(mr) + offset;
+    void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
+    ram_addr_t rb_offset;
     RAMBlock *rb;
     size_t rb_page_size;
-    ram_addr_t ram_offset;
     void *host_addr;
     int ret;
 
     /* XXX is there a better way to get to the RAMBlock than via a
      * host address? */
-    rb = qemu_ram_block_from_host(addr, false, &ram_offset);
+    rb = qemu_ram_block_from_host(addr, false, &rb_offset);
     rb_page_size = qemu_ram_pagesize(rb);
 
     if (balloon->pbp) {
-- 
2.21.0

[Qemu-devel] [PULL 08/12] virtio-balloon: Better names for offset variables in inflate/deflate code

[Michael S. Tsirkin]

From: David Hildenbrand <david@redhat.com>

"host_page_base" is really confusing, let's make this clearer, also
rename the other offsets to indicate to which base they apply.

offset -> mr_offset
ram_offset -> rb_offset
host_page_base -> rb_aligned_offset

While at it, use QEMU_ALIGN_DOWN() instead of a handcrafted computation
and move the computation to the place where it is needed.

Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20190722134108.22151-5-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/virtio/virtio-balloon.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 04a7e6c772..f206cc8bf7 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -41,24 +41,23 @@ struct PartiallyBalloonedPage {
 };
 
 static void balloon_inflate_page(VirtIOBalloon *balloon,
-                                 MemoryRegion *mr, hwaddr offset)
+                                 MemoryRegion *mr, hwaddr mr_offset)
 {
-    void *addr = memory_region_get_ram_ptr(mr) + offset;
+    void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
+    ram_addr_t rb_offset, rb_aligned_offset;
     RAMBlock *rb;
     size_t rb_page_size;
     int subpages;
-    ram_addr_t ram_offset, host_page_base;
 
     /* XXX is there a better way to get to the RAMBlock than via a
      * host address? */
-    rb = qemu_ram_block_from_host(addr, false, &ram_offset);
+    rb = qemu_ram_block_from_host(addr, false, &rb_offset);
     rb_page_size = qemu_ram_pagesize(rb);
-    host_page_base = ram_offset & ~(rb_page_size - 1);
 
     if (rb_page_size == BALLOON_PAGE_SIZE) {
         /* Easy case */
 
-        ram_block_discard_range(rb, ram_offset, rb_page_size);
+        ram_block_discard_range(rb, rb_offset, rb_page_size);
         /* We ignore errors from ram_block_discard_range(), because it
          * has already reported them, and failing to discard a balloon
          * page is not fatal */
@@ -74,11 +73,12 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
     warn_report_once(
 "Balloon used with backing page size > 4kiB, this may not be reliable");
 
+    rb_aligned_offset = QEMU_ALIGN_DOWN(rb_offset, rb_page_size);
     subpages = rb_page_size / BALLOON_PAGE_SIZE;
 
     if (balloon->pbp
         && (rb != balloon->pbp->rb
-            || host_page_base != balloon->pbp->base)) {
+            || rb_aligned_offset != balloon->pbp->base)) {
         /* We've partially ballooned part of a host page, but now
          * we're trying to balloon part of a different one.  Too hard,
          * give up on the old partial page */
@@ -91,10 +91,10 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
         size_t bitlen = BITS_TO_LONGS(subpages) * sizeof(unsigned long);
         balloon->pbp = g_malloc0(sizeof(PartiallyBalloonedPage) + bitlen);
         balloon->pbp->rb = rb;
-        balloon->pbp->base = host_page_base;
+        balloon->pbp->base = rb_aligned_offset;
     }
 
-    set_bit((ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
+    set_bit((rb_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
             balloon->pbp->bitmap);
 
     if (bitmap_full(balloon->pbp->bitmap, subpages)) {
@@ -112,18 +112,18 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
 }
 
 static void balloon_deflate_page(VirtIOBalloon *balloon,
-                                 MemoryRegion *mr, hwaddr offset)
+                                 MemoryRegion *mr, hwaddr mr_offset)
 {
-    void *addr = memory_region_get_ram_ptr(mr) + offset;
+    void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
+    ram_addr_t rb_offset;
     RAMBlock *rb;
     size_t rb_page_size;
-    ram_addr_t ram_offset;
     void *host_addr;
     int ret;
 
     /* XXX is there a better way to get to the RAMBlock than via a
      * host address? */
-    rb = qemu_ram_block_from_host(addr, false, &ram_offset);
+    rb = qemu_ram_block_from_host(addr, false, &rb_offset);
     rb_page_size = qemu_ram_pagesize(rb);
 
     if (balloon->pbp) {
-- 
MST

[Qemu-devel] [PATCH-for-4.1 v3 5/6] virtio-balloon: Rework pbp tracking data

[David Hildenbrand]

Using the address of a RAMBlock to test for a matching pbp is not really
safe. Instead, let's use the guest physical address of the base page
along with the page size (via the number of subpages).

Also, let's allocate the bitmap separately. This makes the code
easier to read and maintain - we can reuse bitmap_new().

Prepare the code to move the PBP out of the device.

Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE <
                     host page size")
Fixes: b27b32391404 ("virtio-balloon: Fix possible guest memory corruption
                     with inflates & deflates")
Cc: qemu-stable@nongnu.org #v4.0.0
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-balloon.c | 69 +++++++++++++++++++++++++-------------
 1 file changed, 46 insertions(+), 23 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index f206cc8bf7..40d493a31a 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -35,16 +35,44 @@
 #define BALLOON_PAGE_SIZE  (1 << VIRTIO_BALLOON_PFN_SHIFT)
 
 struct PartiallyBalloonedPage {
-    RAMBlock *rb;
-    ram_addr_t base;
-    unsigned long bitmap[];
+    ram_addr_t base_gpa;
+    long subpages;
+    unsigned long *bitmap;
 };
 
+static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
+{
+    if (!pbp) {
+        return;
+    }
+    g_free(pbp->bitmap);
+    g_free(pbp);
+}
+
+static PartiallyBalloonedPage *virtio_balloon_pbp_alloc(ram_addr_t base_gpa,
+                                                        long subpages)
+{
+    PartiallyBalloonedPage *pbp = g_new0(PartiallyBalloonedPage, 1);
+
+    pbp->base_gpa = base_gpa;
+    pbp->subpages = subpages;
+    pbp->bitmap = bitmap_new(subpages);
+
+    return pbp;
+}
+
+static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
+                                       ram_addr_t base_gpa, long subpages)
+{
+    return pbp->subpages == subpages && pbp->base_gpa == base_gpa;
+}
+
 static void balloon_inflate_page(VirtIOBalloon *balloon,
                                  MemoryRegion *mr, hwaddr mr_offset)
 {
     void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
-    ram_addr_t rb_offset, rb_aligned_offset;
+    ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
+    PartiallyBalloonedPage **pbp = &balloon->pbp;
     RAMBlock *rb;
     size_t rb_page_size;
     int subpages;
@@ -75,39 +103,34 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
 
     rb_aligned_offset = QEMU_ALIGN_DOWN(rb_offset, rb_page_size);
     subpages = rb_page_size / BALLOON_PAGE_SIZE;
+    base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
+               (rb_offset - rb_aligned_offset);
 
-    if (balloon->pbp
-        && (rb != balloon->pbp->rb
-            || rb_aligned_offset != balloon->pbp->base)) {
+    if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa, subpages)) {
         /* We've partially ballooned part of a host page, but now
          * we're trying to balloon part of a different one.  Too hard,
          * give up on the old partial page */
-        g_free(balloon->pbp);
-        balloon->pbp = NULL;
+        virtio_balloon_pbp_free(*pbp);
+        *pbp = NULL;
     }
 
-    if (!balloon->pbp) {
-        /* Starting on a new host page */
-        size_t bitlen = BITS_TO_LONGS(subpages) * sizeof(unsigned long);
-        balloon->pbp = g_malloc0(sizeof(PartiallyBalloonedPage) + bitlen);
-        balloon->pbp->rb = rb;
-        balloon->pbp->base = rb_aligned_offset;
+    if (!*pbp) {
+        *pbp = virtio_balloon_pbp_alloc(base_gpa, subpages);
     }
 
-    set_bit((rb_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
-            balloon->pbp->bitmap);
+    set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE,
+            (*pbp)->bitmap);
 
-    if (bitmap_full(balloon->pbp->bitmap, subpages)) {
+    if (bitmap_full((*pbp)->bitmap, subpages)) {
         /* We've accumulated a full host page, we can actually discard
          * it now */
 
-        ram_block_discard_range(rb, balloon->pbp->base, rb_page_size);
+        ram_block_discard_range(rb, rb_aligned_offset, rb_page_size);
         /* We ignore errors from ram_block_discard_range(), because it
          * has already reported them, and failing to discard a balloon
          * page is not fatal */
-
-        g_free(balloon->pbp);
-        balloon->pbp = NULL;
+        virtio_balloon_pbp_free(*pbp);
+        *pbp = NULL;
     }
 }
 
@@ -128,7 +151,7 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
 
     if (balloon->pbp) {
         /* Let's play safe and always reset the pbp on deflation requests. */
-        g_free(balloon->pbp);
+        virtio_balloon_pbp_free(balloon->pbp);
         balloon->pbp = NULL;
     }
 
-- 
2.21.0

[Qemu-devel] [PULL 09/12] virtio-balloon: Rework pbp tracking data

[Michael S. Tsirkin]

From: David Hildenbrand <david@redhat.com>

Using the address of a RAMBlock to test for a matching pbp is not really
safe. Instead, let's use the guest physical address of the base page
along with the page size (via the number of subpages).

Also, let's allocate the bitmap separately. This makes the code
easier to read and maintain - we can reuse bitmap_new().

Prepare the code to move the PBP out of the device.

Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE < host page size")
Fixes: b27b32391404 ("virtio-balloon: Fix possible guest memory corruption with inflates & deflates")
Cc: qemu-stable@nongnu.org #v4.0.0
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20190722134108.22151-6-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/virtio/virtio-balloon.c | 69 +++++++++++++++++++++++++-------------
 1 file changed, 46 insertions(+), 23 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index f206cc8bf7..40d493a31a 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -35,16 +35,44 @@
 #define BALLOON_PAGE_SIZE  (1 << VIRTIO_BALLOON_PFN_SHIFT)
 
 struct PartiallyBalloonedPage {
-    RAMBlock *rb;
-    ram_addr_t base;
-    unsigned long bitmap[];
+    ram_addr_t base_gpa;
+    long subpages;
+    unsigned long *bitmap;
 };
 
+static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
+{
+    if (!pbp) {
+        return;
+    }
+    g_free(pbp->bitmap);
+    g_free(pbp);
+}
+
+static PartiallyBalloonedPage *virtio_balloon_pbp_alloc(ram_addr_t base_gpa,
+                                                        long subpages)
+{
+    PartiallyBalloonedPage *pbp = g_new0(PartiallyBalloonedPage, 1);
+
+    pbp->base_gpa = base_gpa;
+    pbp->subpages = subpages;
+    pbp->bitmap = bitmap_new(subpages);
+
+    return pbp;
+}
+
+static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
+                                       ram_addr_t base_gpa, long subpages)
+{
+    return pbp->subpages == subpages && pbp->base_gpa == base_gpa;
+}
+
 static void balloon_inflate_page(VirtIOBalloon *balloon,
                                  MemoryRegion *mr, hwaddr mr_offset)
 {
     void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
-    ram_addr_t rb_offset, rb_aligned_offset;
+    ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
+    PartiallyBalloonedPage **pbp = &balloon->pbp;
     RAMBlock *rb;
     size_t rb_page_size;
     int subpages;
@@ -75,39 +103,34 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
 
     rb_aligned_offset = QEMU_ALIGN_DOWN(rb_offset, rb_page_size);
     subpages = rb_page_size / BALLOON_PAGE_SIZE;
+    base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
+               (rb_offset - rb_aligned_offset);
 
-    if (balloon->pbp
-        && (rb != balloon->pbp->rb
-            || rb_aligned_offset != balloon->pbp->base)) {
+    if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa, subpages)) {
         /* We've partially ballooned part of a host page, but now
          * we're trying to balloon part of a different one.  Too hard,
          * give up on the old partial page */
-        g_free(balloon->pbp);
-        balloon->pbp = NULL;
+        virtio_balloon_pbp_free(*pbp);
+        *pbp = NULL;
     }
 
-    if (!balloon->pbp) {
-        /* Starting on a new host page */
-        size_t bitlen = BITS_TO_LONGS(subpages) * sizeof(unsigned long);
-        balloon->pbp = g_malloc0(sizeof(PartiallyBalloonedPage) + bitlen);
-        balloon->pbp->rb = rb;
-        balloon->pbp->base = rb_aligned_offset;
+    if (!*pbp) {
+        *pbp = virtio_balloon_pbp_alloc(base_gpa, subpages);
     }
 
-    set_bit((rb_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
-            balloon->pbp->bitmap);
+    set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE,
+            (*pbp)->bitmap);
 
-    if (bitmap_full(balloon->pbp->bitmap, subpages)) {
+    if (bitmap_full((*pbp)->bitmap, subpages)) {
         /* We've accumulated a full host page, we can actually discard
          * it now */
 
-        ram_block_discard_range(rb, balloon->pbp->base, rb_page_size);
+        ram_block_discard_range(rb, rb_aligned_offset, rb_page_size);
         /* We ignore errors from ram_block_discard_range(), because it
          * has already reported them, and failing to discard a balloon
          * page is not fatal */
-
-        g_free(balloon->pbp);
-        balloon->pbp = NULL;
+        virtio_balloon_pbp_free(*pbp);
+        *pbp = NULL;
     }
 }
 
@@ -128,7 +151,7 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
 
     if (balloon->pbp) {
         /* Let's play safe and always reset the pbp on deflation requests. */
-        g_free(balloon->pbp);
+        virtio_balloon_pbp_free(balloon->pbp);
         balloon->pbp = NULL;
     }
 
-- 
MST

Re: [Qemu-devel] [PATCH-for-4.1 v3 5/6] virtio-balloon: Rework pbp tracking data

[David Gibson]

[-- Attachment #1: Type: text/plain, Size: 5675 bytes --]

On Mon, Jul 22, 2019 at 03:41:07PM +0200, David Hildenbrand wrote:
> Using the address of a RAMBlock to test for a matching pbp is not really
> safe. Instead, let's use the guest physical address of the base page
> along with the page size (via the number of subpages).
> 
> Also, let's allocate the bitmap separately. This makes the code
> easier to read and maintain - we can reuse bitmap_new().
> 
> Prepare the code to move the PBP out of the device.
> 
> Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE <
>                      host page size")
> Fixes: b27b32391404 ("virtio-balloon: Fix possible guest memory corruption
>                      with inflates & deflates")
> Cc: qemu-stable@nongnu.org #v4.0.0
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  hw/virtio/virtio-balloon.c | 69 +++++++++++++++++++++++++-------------
>  1 file changed, 46 insertions(+), 23 deletions(-)
> 
> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> index f206cc8bf7..40d493a31a 100644
> --- a/hw/virtio/virtio-balloon.c
> +++ b/hw/virtio/virtio-balloon.c
> @@ -35,16 +35,44 @@
>  #define BALLOON_PAGE_SIZE  (1 << VIRTIO_BALLOON_PFN_SHIFT)
>  
>  struct PartiallyBalloonedPage {
> -    RAMBlock *rb;
> -    ram_addr_t base;
> -    unsigned long bitmap[];
> +    ram_addr_t base_gpa;
> +    long subpages;
> +    unsigned long *bitmap;
>  };
>  
> +static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
> +{
> +    if (!pbp) {
> +        return;
> +    }
> +    g_free(pbp->bitmap);
> +    g_free(pbp);
> +}
> +
> +static PartiallyBalloonedPage *virtio_balloon_pbp_alloc(ram_addr_t base_gpa,
> +                                                        long subpages)
> +{
> +    PartiallyBalloonedPage *pbp = g_new0(PartiallyBalloonedPage, 1);
> +
> +    pbp->base_gpa = base_gpa;
> +    pbp->subpages = subpages;
> +    pbp->bitmap = bitmap_new(subpages);
> +
> +    return pbp;
> +}
> +
> +static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
> +                                       ram_addr_t base_gpa, long subpages)
> +{
> +    return pbp->subpages == subpages && pbp->base_gpa == base_gpa;

I think the test on subpages is pointless here.  You've (reasonably)
rejected handling the edge case of a ramblock being removed and
replugged - but the only thing this handles is an edge case of that
edge case.


Otherwise, LGTM.

> +}
> +
>  static void balloon_inflate_page(VirtIOBalloon *balloon,
>                                   MemoryRegion *mr, hwaddr mr_offset)
>  {
>      void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
> -    ram_addr_t rb_offset, rb_aligned_offset;
> +    ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
> +    PartiallyBalloonedPage **pbp = &balloon->pbp;
>      RAMBlock *rb;
>      size_t rb_page_size;
>      int subpages;
> @@ -75,39 +103,34 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
>  
>      rb_aligned_offset = QEMU_ALIGN_DOWN(rb_offset, rb_page_size);
>      subpages = rb_page_size / BALLOON_PAGE_SIZE;
> +    base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
> +               (rb_offset - rb_aligned_offset);
>  
> -    if (balloon->pbp
> -        && (rb != balloon->pbp->rb
> -            || rb_aligned_offset != balloon->pbp->base)) {
> +    if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa, subpages)) {
>          /* We've partially ballooned part of a host page, but now
>           * we're trying to balloon part of a different one.  Too hard,
>           * give up on the old partial page */
> -        g_free(balloon->pbp);
> -        balloon->pbp = NULL;
> +        virtio_balloon_pbp_free(*pbp);
> +        *pbp = NULL;
>      }
>  
> -    if (!balloon->pbp) {
> -        /* Starting on a new host page */
> -        size_t bitlen = BITS_TO_LONGS(subpages) * sizeof(unsigned long);
> -        balloon->pbp = g_malloc0(sizeof(PartiallyBalloonedPage) + bitlen);
> -        balloon->pbp->rb = rb;
> -        balloon->pbp->base = rb_aligned_offset;
> +    if (!*pbp) {
> +        *pbp = virtio_balloon_pbp_alloc(base_gpa, subpages);
>      }
>  
> -    set_bit((rb_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE,
> -            balloon->pbp->bitmap);
> +    set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE,
> +            (*pbp)->bitmap);
>  
> -    if (bitmap_full(balloon->pbp->bitmap, subpages)) {
> +    if (bitmap_full((*pbp)->bitmap, subpages)) {
>          /* We've accumulated a full host page, we can actually discard
>           * it now */
>  
> -        ram_block_discard_range(rb, balloon->pbp->base, rb_page_size);
> +        ram_block_discard_range(rb, rb_aligned_offset, rb_page_size);
>          /* We ignore errors from ram_block_discard_range(), because it
>           * has already reported them, and failing to discard a balloon
>           * page is not fatal */
> -
> -        g_free(balloon->pbp);
> -        balloon->pbp = NULL;
> +        virtio_balloon_pbp_free(*pbp);
> +        *pbp = NULL;
>      }
>  }
>  
> @@ -128,7 +151,7 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
>  
>      if (balloon->pbp) {
>          /* Let's play safe and always reset the pbp on deflation requests. */
> -        g_free(balloon->pbp);
> +        virtio_balloon_pbp_free(balloon->pbp);
>          balloon->pbp = NULL;
>      }
>  

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [Qemu-devel] [PATCH-for-4.1 v3 5/6] virtio-balloon: Rework pbp tracking data

[David Hildenbrand]

On 23.07.19 04:54, David Gibson wrote:
> On Mon, Jul 22, 2019 at 03:41:07PM +0200, David Hildenbrand wrote:
>> Using the address of a RAMBlock to test for a matching pbp is not really
>> safe. Instead, let's use the guest physical address of the base page
>> along with the page size (via the number of subpages).
>>
>> Also, let's allocate the bitmap separately. This makes the code
>> easier to read and maintain - we can reuse bitmap_new().
>>
>> Prepare the code to move the PBP out of the device.
>>
>> Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE <
>>                      host page size")
>> Fixes: b27b32391404 ("virtio-balloon: Fix possible guest memory corruption
>>                      with inflates & deflates")
>> Cc: qemu-stable@nongnu.org #v4.0.0
>> Signed-off-by: David Hildenbrand <david@redhat.com>
>> ---
>>  hw/virtio/virtio-balloon.c | 69 +++++++++++++++++++++++++-------------
>>  1 file changed, 46 insertions(+), 23 deletions(-)
>>
>> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
>> index f206cc8bf7..40d493a31a 100644
>> --- a/hw/virtio/virtio-balloon.c
>> +++ b/hw/virtio/virtio-balloon.c
>> @@ -35,16 +35,44 @@
>>  #define BALLOON_PAGE_SIZE  (1 << VIRTIO_BALLOON_PFN_SHIFT)
>>  
>>  struct PartiallyBalloonedPage {
>> -    RAMBlock *rb;
>> -    ram_addr_t base;
>> -    unsigned long bitmap[];
>> +    ram_addr_t base_gpa;
>> +    long subpages;
>> +    unsigned long *bitmap;
>>  };
>>  
>> +static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
>> +{
>> +    if (!pbp) {
>> +        return;
>> +    }
>> +    g_free(pbp->bitmap);
>> +    g_free(pbp);
>> +}
>> +
>> +static PartiallyBalloonedPage *virtio_balloon_pbp_alloc(ram_addr_t base_gpa,
>> +                                                        long subpages)
>> +{
>> +    PartiallyBalloonedPage *pbp = g_new0(PartiallyBalloonedPage, 1);
>> +
>> +    pbp->base_gpa = base_gpa;
>> +    pbp->subpages = subpages;
>> +    pbp->bitmap = bitmap_new(subpages);
>> +
>> +    return pbp;
>> +}
>> +
>> +static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
>> +                                       ram_addr_t base_gpa, long subpages)
>> +{
>> +    return pbp->subpages == subpages && pbp->base_gpa == base_gpa;
> 
> I think the test on subpages is pointless here.  You've (reasonably)
> rejected handling the edge case of a ramblock being removed and
> replugged - but the only thing this handles is an edge case of that
> edge case.

I think we have to leave it in place until patch #6. We could remove it
after Patch #6 - replug cannot happen while processing the inflation
requests.

-- 

Thanks,

David / dhildenb

[Qemu-devel] [PATCH-for-4.1 v3 6/6] virtio-balloon: Use temporary PBP only

[David Hildenbrand]

We still have multiple issues in the current code
- The PBP is not freed during unrealize()
- The PBP is not reset on device resets: After a reset, the PBP is stale.
- We are not indicating VIRTIO_BALLOON_F_MUST_TELL_HOST, therefore
  guests (esp. legacy guests) will reuse pages without deflating,
  turning the PBP stale. Adding that would require compat handling.

Instead, let's use the PBP only temporarily, when processing one bulk of
inflation requests. This will keep guest_page_size > 4k working (with
Linux guests). There is nothing to do for deflation requests anymore.
The pbp is only used for a limited amount of time.

Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE <
                     host page size")
Cc: qemu-stable@nongnu.org #v4.0.0
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-balloon.c         | 21 +++++++++------------
 include/hw/virtio/virtio-balloon.h |  3 ---
 2 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 40d493a31a..a6282d58d4 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -34,11 +34,11 @@
 
 #define BALLOON_PAGE_SIZE  (1 << VIRTIO_BALLOON_PFN_SHIFT)
 
-struct PartiallyBalloonedPage {
+typedef struct PartiallyBalloonedPage {
     ram_addr_t base_gpa;
     long subpages;
     unsigned long *bitmap;
-};
+} PartiallyBalloonedPage;
 
 static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
 {
@@ -68,11 +68,11 @@ static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
 }
 
 static void balloon_inflate_page(VirtIOBalloon *balloon,
-                                 MemoryRegion *mr, hwaddr mr_offset)
+                                 MemoryRegion *mr, hwaddr mr_offset,
+                                 PartiallyBalloonedPage **pbp)
 {
     void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
     ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
-    PartiallyBalloonedPage **pbp = &balloon->pbp;
     RAMBlock *rb;
     size_t rb_page_size;
     int subpages;
@@ -149,12 +149,6 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
     rb = qemu_ram_block_from_host(addr, false, &rb_offset);
     rb_page_size = qemu_ram_pagesize(rb);
 
-    if (balloon->pbp) {
-        /* Let's play safe and always reset the pbp on deflation requests. */
-        virtio_balloon_pbp_free(balloon->pbp);
-        balloon->pbp = NULL;
-    }
-
     host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1));
 
     /* When a page is deflated, we hint the whole host page it lives
@@ -336,6 +330,7 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
+    PartiallyBalloonedPage *pbp = NULL;
     VirtQueueElement *elem;
     MemoryRegionSection section;
 
@@ -344,7 +339,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
         uint32_t pfn;
         elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
         if (!elem) {
-            return;
+            break;
         }
 
         while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
@@ -373,7 +368,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
             if (!qemu_balloon_is_inhibited()) {
                 if (vq == s->ivq) {
                     balloon_inflate_page(s, section.mr,
-                                         section.offset_within_region);
+                                         section.offset_within_region, &pbp);
                 } else if (vq == s->dvq) {
                     balloon_deflate_page(s, section.mr, section.offset_within_region);
                 } else {
@@ -387,6 +382,8 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
         virtio_notify(vdev, vq);
         g_free(elem);
     }
+
+    virtio_balloon_pbp_free(pbp);
 }
 
 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h
index 5a99293a45..d1c968d237 100644
--- a/include/hw/virtio/virtio-balloon.h
+++ b/include/hw/virtio/virtio-balloon.h
@@ -33,8 +33,6 @@ typedef struct virtio_balloon_stat_modern {
        uint64_t val;
 } VirtIOBalloonStatModern;
 
-typedef struct PartiallyBalloonedPage PartiallyBalloonedPage;
-
 enum virtio_balloon_free_page_report_status {
     FREE_PAGE_REPORT_S_STOP = 0,
     FREE_PAGE_REPORT_S_REQUESTED = 1,
@@ -70,7 +68,6 @@ typedef struct VirtIOBalloon {
     int64_t stats_last_update;
     int64_t stats_poll_interval;
     uint32_t host_features;
-    PartiallyBalloonedPage *pbp;
 
     bool qemu_4_0_config_size;
 } VirtIOBalloon;
-- 
2.21.0

[Qemu-devel] [PULL 10/12] virtio-balloon: Use temporary PBP only

[Michael S. Tsirkin]

From: David Hildenbrand <david@redhat.com>

We still have multiple issues in the current code
- The PBP is not freed during unrealize()
- The PBP is not reset on device resets: After a reset, the PBP is stale.
- We are not indicating VIRTIO_BALLOON_F_MUST_TELL_HOST, therefore
  guests (esp. legacy guests) will reuse pages without deflating,
  turning the PBP stale. Adding that would require compat handling.

Instead, let's use the PBP only temporarily, when processing one bulk of
inflation requests. This will keep guest_page_size > 4k working (with
Linux guests). There is nothing to do for deflation requests anymore.
The pbp is only used for a limited amount of time.

Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE < host page size")
Cc: qemu-stable@nongnu.org #v4.0.0
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20190722134108.22151-7-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/virtio/virtio-balloon.c         | 21 +++++++++------------
 include/hw/virtio/virtio-balloon.h |  3 ---
 2 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 40d493a31a..a6282d58d4 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -34,11 +34,11 @@
 
 #define BALLOON_PAGE_SIZE  (1 << VIRTIO_BALLOON_PFN_SHIFT)
 
-struct PartiallyBalloonedPage {
+typedef struct PartiallyBalloonedPage {
     ram_addr_t base_gpa;
     long subpages;
     unsigned long *bitmap;
-};
+} PartiallyBalloonedPage;
 
 static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
 {
@@ -68,11 +68,11 @@ static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
 }
 
 static void balloon_inflate_page(VirtIOBalloon *balloon,
-                                 MemoryRegion *mr, hwaddr mr_offset)
+                                 MemoryRegion *mr, hwaddr mr_offset,
+                                 PartiallyBalloonedPage **pbp)
 {
     void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
     ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
-    PartiallyBalloonedPage **pbp = &balloon->pbp;
     RAMBlock *rb;
     size_t rb_page_size;
     int subpages;
@@ -149,12 +149,6 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
     rb = qemu_ram_block_from_host(addr, false, &rb_offset);
     rb_page_size = qemu_ram_pagesize(rb);
 
-    if (balloon->pbp) {
-        /* Let's play safe and always reset the pbp on deflation requests. */
-        virtio_balloon_pbp_free(balloon->pbp);
-        balloon->pbp = NULL;
-    }
-
     host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1));
 
     /* When a page is deflated, we hint the whole host page it lives
@@ -336,6 +330,7 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
+    PartiallyBalloonedPage *pbp = NULL;
     VirtQueueElement *elem;
     MemoryRegionSection section;
 
@@ -344,7 +339,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
         uint32_t pfn;
         elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
         if (!elem) {
-            return;
+            break;
         }
 
         while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
@@ -373,7 +368,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
             if (!qemu_balloon_is_inhibited()) {
                 if (vq == s->ivq) {
                     balloon_inflate_page(s, section.mr,
-                                         section.offset_within_region);
+                                         section.offset_within_region, &pbp);
                 } else if (vq == s->dvq) {
                     balloon_deflate_page(s, section.mr, section.offset_within_region);
                 } else {
@@ -387,6 +382,8 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
         virtio_notify(vdev, vq);
         g_free(elem);
     }
+
+    virtio_balloon_pbp_free(pbp);
 }
 
 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h
index 5a99293a45..d1c968d237 100644
--- a/include/hw/virtio/virtio-balloon.h
+++ b/include/hw/virtio/virtio-balloon.h
@@ -33,8 +33,6 @@ typedef struct virtio_balloon_stat_modern {
        uint64_t val;
 } VirtIOBalloonStatModern;
 
-typedef struct PartiallyBalloonedPage PartiallyBalloonedPage;
-
 enum virtio_balloon_free_page_report_status {
     FREE_PAGE_REPORT_S_STOP = 0,
     FREE_PAGE_REPORT_S_REQUESTED = 1,
@@ -70,7 +68,6 @@ typedef struct VirtIOBalloon {
     int64_t stats_last_update;
     int64_t stats_poll_interval;
     uint32_t host_features;
-    PartiallyBalloonedPage *pbp;
 
     bool qemu_4_0_config_size;
 } VirtIOBalloon;
-- 
MST

Re: [Qemu-devel] [PATCH-for-4.1 v3 6/6] virtio-balloon: Use temporary PBP only

[David Gibson]

[-- Attachment #1: Type: text/plain, Size: 5581 bytes --]

On Mon, Jul 22, 2019 at 03:41:08PM +0200, David Hildenbrand wrote:
> We still have multiple issues in the current code
> - The PBP is not freed during unrealize()
> - The PBP is not reset on device resets: After a reset, the PBP is stale.
> - We are not indicating VIRTIO_BALLOON_F_MUST_TELL_HOST, therefore
>   guests (esp. legacy guests) will reuse pages without deflating,
>   turning the PBP stale. Adding that would require compat handling.
> 
> Instead, let's use the PBP only temporarily, when processing one bulk of
> inflation requests. This will keep guest_page_size > 4k working (with
> Linux guests). There is nothing to do for deflation requests anymore.
> The pbp is only used for a limited amount of time.
> 
> Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE <
>                      host page size")
> Cc: qemu-stable@nongnu.org #v4.0.0
> Suggested-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Ah, nice idea.  

Acked-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  hw/virtio/virtio-balloon.c         | 21 +++++++++------------
>  include/hw/virtio/virtio-balloon.h |  3 ---
>  2 files changed, 9 insertions(+), 15 deletions(-)
> 
> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> index 40d493a31a..a6282d58d4 100644
> --- a/hw/virtio/virtio-balloon.c
> +++ b/hw/virtio/virtio-balloon.c
> @@ -34,11 +34,11 @@
>  
>  #define BALLOON_PAGE_SIZE  (1 << VIRTIO_BALLOON_PFN_SHIFT)
>  
> -struct PartiallyBalloonedPage {
> +typedef struct PartiallyBalloonedPage {
>      ram_addr_t base_gpa;
>      long subpages;
>      unsigned long *bitmap;
> -};
> +} PartiallyBalloonedPage;
>  
>  static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
>  {
> @@ -68,11 +68,11 @@ static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
>  }
>  
>  static void balloon_inflate_page(VirtIOBalloon *balloon,
> -                                 MemoryRegion *mr, hwaddr mr_offset)
> +                                 MemoryRegion *mr, hwaddr mr_offset,
> +                                 PartiallyBalloonedPage **pbp)
>  {
>      void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
>      ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
> -    PartiallyBalloonedPage **pbp = &balloon->pbp;
>      RAMBlock *rb;
>      size_t rb_page_size;
>      int subpages;
> @@ -149,12 +149,6 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
>      rb = qemu_ram_block_from_host(addr, false, &rb_offset);
>      rb_page_size = qemu_ram_pagesize(rb);
>  
> -    if (balloon->pbp) {
> -        /* Let's play safe and always reset the pbp on deflation requests. */
> -        virtio_balloon_pbp_free(balloon->pbp);
> -        balloon->pbp = NULL;
> -    }
> -
>      host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1));
>  
>      /* When a page is deflated, we hint the whole host page it lives
> @@ -336,6 +330,7 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
>  static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>  {
>      VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
> +    PartiallyBalloonedPage *pbp = NULL;
>      VirtQueueElement *elem;
>      MemoryRegionSection section;
>  
> @@ -344,7 +339,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>          uint32_t pfn;
>          elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
>          if (!elem) {
> -            return;
> +            break;
>          }
>  
>          while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
> @@ -373,7 +368,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>              if (!qemu_balloon_is_inhibited()) {
>                  if (vq == s->ivq) {
>                      balloon_inflate_page(s, section.mr,
> -                                         section.offset_within_region);
> +                                         section.offset_within_region, &pbp);
>                  } else if (vq == s->dvq) {
>                      balloon_deflate_page(s, section.mr, section.offset_within_region);
>                  } else {
> @@ -387,6 +382,8 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>          virtio_notify(vdev, vq);
>          g_free(elem);
>      }
> +
> +    virtio_balloon_pbp_free(pbp);
>  }
>  
>  static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
> diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h
> index 5a99293a45..d1c968d237 100644
> --- a/include/hw/virtio/virtio-balloon.h
> +++ b/include/hw/virtio/virtio-balloon.h
> @@ -33,8 +33,6 @@ typedef struct virtio_balloon_stat_modern {
>         uint64_t val;
>  } VirtIOBalloonStatModern;
>  
> -typedef struct PartiallyBalloonedPage PartiallyBalloonedPage;
> -
>  enum virtio_balloon_free_page_report_status {
>      FREE_PAGE_REPORT_S_STOP = 0,
>      FREE_PAGE_REPORT_S_REQUESTED = 1,
> @@ -70,7 +68,6 @@ typedef struct VirtIOBalloon {
>      int64_t stats_last_update;
>      int64_t stats_poll_interval;
>      uint32_t host_features;
> -    PartiallyBalloonedPage *pbp;
>  
>      bool qemu_4_0_config_size;
>  } VirtIOBalloon;

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

[Qemu-devel] [PATCH] i386/acpi: show PCI Express bus on pxb-pcie expanders

[Evgeny Yakovlev]

Show PCIe host bridge PNP id with PCI host bridge as a compatible id
when expanding a pcie bus.

Signed-off-by: Evgeny Yakovlev <wrfsh@yandex-team.ru>
---
 hw/i386/acpi-build.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index d281ffa..0675952 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -1908,10 +1908,13 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
             scope = aml_scope("\\_SB");
             dev = aml_device("PC%.02X", bus_num);
             aml_append(dev, aml_name_decl("_UID", aml_int(bus_num)));
-            aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A03")));
             aml_append(dev, aml_name_decl("_BBN", aml_int(bus_num)));
             if (pci_bus_is_express(bus)) {
+                aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A08")));
+                aml_append(dev, aml_name_decl("_CID", aml_eisaid("PNP0A03")));
                 aml_append(dev, build_q35_osc_method());
+            } else {
+                aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A03")));
             }
 
             if (numa_node != NUMA_NODE_UNASSIGNED) {
-- 
2.7.4

[Qemu-devel] [PULL 04/12] i386/acpi: show PCI Express bus on pxb-pcie expanders

[Michael S. Tsirkin]

From: Evgeny Yakovlev <wrfsh@yandex-team.ru>

Show PCIe host bridge PNP id with PCI host bridge as a compatible id
when expanding a pcie bus.

Cc: qemu-stable@nongnu.org
Signed-off-by: Evgeny Yakovlev <wrfsh@yandex-team.ru>
Message-Id: <1563526469-15588-1-git-send-email-wrfsh@yandex-team.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/i386/acpi-build.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index e7b756b51b..f3fdfefcd5 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -1914,10 +1914,13 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
             scope = aml_scope("\\_SB");
             dev = aml_device("PC%.02X", bus_num);
             aml_append(dev, aml_name_decl("_UID", aml_int(bus_num)));
-            aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A03")));
             aml_append(dev, aml_name_decl("_BBN", aml_int(bus_num)));
             if (pci_bus_is_express(bus)) {
+                aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A08")));
+                aml_append(dev, aml_name_decl("_CID", aml_eisaid("PNP0A03")));
                 aml_append(dev, build_q35_osc_method());
+            } else {
+                aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A03")));
             }
 
             if (numa_node != NUMA_NODE_UNASSIGNED) {
-- 
MST

Re: [Qemu-devel] [PATCH] i386/acpi: show PCI Express bus on pxb-pcie expanders

[Igor Mammedov]

On Fri, 19 Jul 2019 11:54:29 +0300
Evgeny Yakovlev <wrfsh@yandex-team.ru> wrote:

> Show PCIe host bridge PNP id with PCI host bridge as a compatible id
> when expanding a pcie bus.
> 
> Signed-off-by: Evgeny Yakovlev <wrfsh@yandex-team.ru>

Reviewed-by: Igor Mammedov <imammedo@redhat.com>

> ---
>  hw/i386/acpi-build.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index d281ffa..0675952 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1908,10 +1908,13 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
>              scope = aml_scope("\\_SB");
>              dev = aml_device("PC%.02X", bus_num);
>              aml_append(dev, aml_name_decl("_UID", aml_int(bus_num)));
> -            aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A03")));
>              aml_append(dev, aml_name_decl("_BBN", aml_int(bus_num)));
>              if (pci_bus_is_express(bus)) {
> +                aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A08")));
> +                aml_append(dev, aml_name_decl("_CID", aml_eisaid("PNP0A03")));
>                  aml_append(dev, build_q35_osc_method());
> +            } else {
> +                aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A03")));
>              }
>  
>              if (numa_node != NUMA_NODE_UNASSIGNED) {

[Qemu-devel] [PATCH v2] i386/acpi: fix gint overflow in crs_range_compare

[Evgeny Yakovlev]

When very large regions (32GB sized in our case, PCI pass-through of GPUs)
are compared substraction result does not fit into gint.

As a result crs_replace_with_free_ranges does not get sorted ranges and
incorrectly computes PCI64 free space regions. Which then makes linux
guest complain about device and PCI64 hole intersection and device
becomes unusable.

Fix that by returning exactly fitting ranges.

Also fix indentation of an entire crs_replace_with_free_ranges to make
checkpatch happy.

Signed-off-by: Evgeny Yakovlev <wrfsh@yandex-team.ru>
---
v2:
entire crs_replace_with_free_ranges was indented with 5 spaces, including my change.
fix that as well

 hw/i386/acpi-build.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index d281ffa..e7b756b 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -755,10 +755,16 @@ static void crs_range_set_free(CrsRangeSet *range_set)
 
 static gint crs_range_compare(gconstpointer a, gconstpointer b)
 {
-     CrsRangeEntry *entry_a = *(CrsRangeEntry **)a;
-     CrsRangeEntry *entry_b = *(CrsRangeEntry **)b;
+    CrsRangeEntry *entry_a = *(CrsRangeEntry **)a;
+    CrsRangeEntry *entry_b = *(CrsRangeEntry **)b;
 
-     return (int64_t)entry_a->base - (int64_t)entry_b->base;
+    if (entry_a->base < entry_b->base) {
+        return -1;
+    } else if (entry_a->base > entry_b->base) {
+        return 1;
+    } else {
+        return 0;
+    }
 }
 
 /*
-- 
2.7.4

[Qemu-devel] [PULL 02/12] i386/acpi: fix gint overflow in crs_range_compare

[Michael S. Tsirkin]

From: Evgeny Yakovlev <wrfsh@yandex-team.ru>

When very large regions (32GB sized in our case, PCI pass-through of GPUs)
are compared substraction result does not fit into gint.

As a result crs_replace_with_free_ranges does not get sorted ranges and
incorrectly computes PCI64 free space regions. Which then makes linux
guest complain about device and PCI64 hole intersection and device
becomes unusable.

Fix that by returning exactly fitting ranges.

Also fix indentation of an entire crs_replace_with_free_ranges to make
checkpatch happy.

Cc: qemu-stable@nongnu.org
Signed-off-by: Evgeny Yakovlev <wrfsh@yandex-team.ru>
Message-Id: <1563466463-26012-1-git-send-email-wrfsh@yandex-team.ru>
Signed-off-by: Evgeny Yakovlev <wrfsh@yandex-team.ru>
---
 hw/i386/acpi-build.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index d281ffa89e..e7b756b51b 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -755,10 +755,16 @@ static void crs_range_set_free(CrsRangeSet *range_set)
 
 static gint crs_range_compare(gconstpointer a, gconstpointer b)
 {
-     CrsRangeEntry *entry_a = *(CrsRangeEntry **)a;
-     CrsRangeEntry *entry_b = *(CrsRangeEntry **)b;
+    CrsRangeEntry *entry_a = *(CrsRangeEntry **)a;
+    CrsRangeEntry *entry_b = *(CrsRangeEntry **)b;
 
-     return (int64_t)entry_a->base - (int64_t)entry_b->base;
+    if (entry_a->base < entry_b->base) {
+        return -1;
+    } else if (entry_a->base > entry_b->base) {
+        return 1;
+    } else {
+        return 0;
+    }
 }
 
 /*
-- 
MST

Re: [Qemu-devel] [PATCH v2] i386/acpi: fix gint overflow in crs_range_compare

[Michael S. Tsirkin]

On Thu, Jul 18, 2019 at 07:14:23PM +0300, Evgeny Yakovlev wrote:
> When very large regions (32GB sized in our case, PCI pass-through of GPUs)
> are compared substraction result does not fit into gint.
> 
> As a result crs_replace_with_free_ranges does not get sorted ranges and
> incorrectly computes PCI64 free space regions. Which then makes linux
> guest complain about device and PCI64 hole intersection and device
> becomes unusable.
> 
> Fix that by returning exactly fitting ranges.
> 
> Also fix indentation of an entire crs_replace_with_free_ranges to make
> checkpatch happy.
> 
> Signed-off-by: Evgeny Yakovlev <wrfsh@yandex-team.ru>

queued, thanks a lot!

> ---
> v2:
> entire crs_replace_with_free_ranges was indented with 5 spaces, including my change.
> fix that as well
> 
>  hw/i386/acpi-build.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index d281ffa..e7b756b 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -755,10 +755,16 @@ static void crs_range_set_free(CrsRangeSet *range_set)
>  
>  static gint crs_range_compare(gconstpointer a, gconstpointer b)
>  {
> -     CrsRangeEntry *entry_a = *(CrsRangeEntry **)a;
> -     CrsRangeEntry *entry_b = *(CrsRangeEntry **)b;
> +    CrsRangeEntry *entry_a = *(CrsRangeEntry **)a;
> +    CrsRangeEntry *entry_b = *(CrsRangeEntry **)b;
>  
> -     return (int64_t)entry_a->base - (int64_t)entry_b->base;
> +    if (entry_a->base < entry_b->base) {
> +        return -1;
> +    } else if (entry_a->base > entry_b->base) {
> +        return 1;
> +    } else {
> +        return 0;
> +    }
>  }
>  
>  /*
> -- 
> 2.7.4

[Qemu-devel] [PATCH] docs: clarify multiqueue vs multiple virtqueues

[Stefan Hajnoczi]

The vhost-user specification does not explain when
VHOST_USER_PROTOCOL_F_MQ must be implemented.  This may lead
implementors of vhost-user masters to believe that this protocol feature
is required for any device that has multiple virtqueues.  That would be
a mistake since existing vhost-user slaves offer multiple virtqueues but
do not advertise VHOST_USER_PROTOCOL_F_MQ.

For example, a vhost-net device with one rx/tx queue pair is not
multiqueue.  The slave does not need to advertise
VHOST_USER_PROTOCOL_F_MQ.  Therefore the master must assume it has these
virtqueues and cannot rely on askingt the slave how many virtqueues
exist.

Extend the specification to explain the different between true
multiqueue and regular devices with a fixed virtqueue layout.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
Based-on: <20190621094005.4134-1-stefanha@redhat.com>
---
 docs/interop/vhost-user.rst | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
index 5750668aba..7827b710aa 100644
--- a/docs/interop/vhost-user.rst
+++ b/docs/interop/vhost-user.rst
@@ -324,6 +324,15 @@ must support changing some configuration aspects on the fly.
 Multiple queue support
 ----------------------
 
+Many devices have a fixed number of virtqueues.  In this case the master
+already knows the number of available virtqueues without communicating with the
+slave.
+
+Some devices do not have a fixed number of virtqueues.  Instead the maximum
+number of virtqueues is chosen by the slave.  The number can depend on host
+resource availability or slave implementation details.  Such devices are called
+multiple queue devices.
+
 Multiple queue support allows the slave to advertise the maximum number of
 queues.  This is treated as a protocol extension, hence the slave has to
 implement protocol features first. The multiple queues feature is supported
@@ -339,6 +348,14 @@ queue in the sent message to identify a specified queue.
 The master enables queues by sending message ``VHOST_USER_SET_VRING_ENABLE``.
 vhost-user-net has historically automatically enabled the first queue pair.
 
+Slaves should always implement the ``VHOST_USER_PROTOCOL_F_MQ`` protocol
+feature, even for devices with a fixed number of virtqueues, since it is simple
+to implement and offers a degree of introspection.
+
+Masters must not rely on the ``VHOST_USER_PROTOCOL_F_MQ`` protocol feature for
+devices with a fixed number of virtqueues.  Only true multiqueue devices
+require this protocol feature.
+
 Migration
 ---------
 
-- 
2.21.0

[Qemu-devel] [PULL 01/12] docs: clarify multiqueue vs multiple virtqueues

[Michael S. Tsirkin]

From: Stefan Hajnoczi <stefanha@redhat.com>

The vhost-user specification does not explain when
VHOST_USER_PROTOCOL_F_MQ must be implemented.  This may lead
implementors of vhost-user masters to believe that this protocol feature
is required for any device that has multiple virtqueues.  That would be
a mistake since existing vhost-user slaves offer multiple virtqueues but
do not advertise VHOST_USER_PROTOCOL_F_MQ.

For example, a vhost-net device with one rx/tx queue pair is not
multiqueue.  The slave does not need to advertise
VHOST_USER_PROTOCOL_F_MQ.  Therefore the master must assume it has these
virtqueues and cannot rely on askingt the slave how many virtqueues
exist.

Extend the specification to explain the different between true
multiqueue and regular devices with a fixed virtqueue layout.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20190624091304.666-1-stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 docs/interop/vhost-user.rst | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
index 5750668aba..7827b710aa 100644
--- a/docs/interop/vhost-user.rst
+++ b/docs/interop/vhost-user.rst
@@ -324,6 +324,15 @@ must support changing some configuration aspects on the fly.
 Multiple queue support
 ----------------------
 
+Many devices have a fixed number of virtqueues.  In this case the master
+already knows the number of available virtqueues without communicating with the
+slave.
+
+Some devices do not have a fixed number of virtqueues.  Instead the maximum
+number of virtqueues is chosen by the slave.  The number can depend on host
+resource availability or slave implementation details.  Such devices are called
+multiple queue devices.
+
 Multiple queue support allows the slave to advertise the maximum number of
 queues.  This is treated as a protocol extension, hence the slave has to
 implement protocol features first. The multiple queues feature is supported
@@ -339,6 +348,14 @@ queue in the sent message to identify a specified queue.
 The master enables queues by sending message ``VHOST_USER_SET_VRING_ENABLE``.
 vhost-user-net has historically automatically enabled the first queue pair.
 
+Slaves should always implement the ``VHOST_USER_PROTOCOL_F_MQ`` protocol
+feature, even for devices with a fixed number of virtqueues, since it is simple
+to implement and offers a degree of introspection.
+
+Masters must not rely on the ``VHOST_USER_PROTOCOL_F_MQ`` protocol feature for
+devices with a fixed number of virtqueues.  Only true multiqueue devices
+require this protocol feature.
+
 Migration
 ---------
 
-- 
MST

Re: [Qemu-devel] [PATCH] docs: clarify multiqueue vs multiple virtqueues

[Marc-André Lureau]

Hi

On Mon, Jun 24, 2019 at 11:13 AM Stefan Hajnoczi <stefanha@redhat.com> wrote:
>
> The vhost-user specification does not explain when
> VHOST_USER_PROTOCOL_F_MQ must be implemented.  This may lead
> implementors of vhost-user masters to believe that this protocol feature
> is required for any device that has multiple virtqueues.  That would be
> a mistake since existing vhost-user slaves offer multiple virtqueues but
> do not advertise VHOST_USER_PROTOCOL_F_MQ.
>
> For example, a vhost-net device with one rx/tx queue pair is not
> multiqueue.  The slave does not need to advertise
> VHOST_USER_PROTOCOL_F_MQ.  Therefore the master must assume it has these
> virtqueues and cannot rely on askingt the slave how many virtqueues
> exist.
>
> Extend the specification to explain the different between true
> multiqueue and regular devices with a fixed virtqueue layout.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

> ---
> Based-on: <20190621094005.4134-1-stefanha@redhat.com>
> ---
>  docs/interop/vhost-user.rst | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
>
> diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
> index 5750668aba..7827b710aa 100644
> --- a/docs/interop/vhost-user.rst
> +++ b/docs/interop/vhost-user.rst
> @@ -324,6 +324,15 @@ must support changing some configuration aspects on the fly.
>  Multiple queue support
>  ----------------------
>
> +Many devices have a fixed number of virtqueues.  In this case the master
> +already knows the number of available virtqueues without communicating with the
> +slave.
> +
> +Some devices do not have a fixed number of virtqueues.  Instead the maximum
> +number of virtqueues is chosen by the slave.  The number can depend on host
> +resource availability or slave implementation details.  Such devices are called
> +multiple queue devices.
> +
>  Multiple queue support allows the slave to advertise the maximum number of
>  queues.  This is treated as a protocol extension, hence the slave has to
>  implement protocol features first. The multiple queues feature is supported
> @@ -339,6 +348,14 @@ queue in the sent message to identify a specified queue.
>  The master enables queues by sending message ``VHOST_USER_SET_VRING_ENABLE``.
>  vhost-user-net has historically automatically enabled the first queue pair.
>
> +Slaves should always implement the ``VHOST_USER_PROTOCOL_F_MQ`` protocol
> +feature, even for devices with a fixed number of virtqueues, since it is simple
> +to implement and offers a degree of introspection.
> +
> +Masters must not rely on the ``VHOST_USER_PROTOCOL_F_MQ`` protocol feature for
> +devices with a fixed number of virtqueues.  Only true multiqueue devices
> +require this protocol feature.
> +
>  Migration
>  ---------
>
> --
> 2.21.0
>
>


-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH] docs: clarify multiqueue vs multiple virtqueues

[Stefan Hajnoczi]

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On Mon, Jun 24, 2019 at 10:13:04AM +0100, Stefan Hajnoczi wrote:
> The vhost-user specification does not explain when
> VHOST_USER_PROTOCOL_F_MQ must be implemented.  This may lead
> implementors of vhost-user masters to believe that this protocol feature
> is required for any device that has multiple virtqueues.  That would be
> a mistake since existing vhost-user slaves offer multiple virtqueues but
> do not advertise VHOST_USER_PROTOCOL_F_MQ.
> 
> For example, a vhost-net device with one rx/tx queue pair is not
> multiqueue.  The slave does not need to advertise
> VHOST_USER_PROTOCOL_F_MQ.  Therefore the master must assume it has these
> virtqueues and cannot rely on askingt the slave how many virtqueues
> exist.
> 
> Extend the specification to explain the different between true
> multiqueue and regular devices with a fixed virtqueue layout.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> Based-on: <20190621094005.4134-1-stefanha@redhat.com>
> ---
>  docs/interop/vhost-user.rst | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)

Ping?

> 
> diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
> index 5750668aba..7827b710aa 100644
> --- a/docs/interop/vhost-user.rst
> +++ b/docs/interop/vhost-user.rst
> @@ -324,6 +324,15 @@ must support changing some configuration aspects on the fly.
>  Multiple queue support
>  ----------------------
>  
> +Many devices have a fixed number of virtqueues.  In this case the master
> +already knows the number of available virtqueues without communicating with the
> +slave.
> +
> +Some devices do not have a fixed number of virtqueues.  Instead the maximum
> +number of virtqueues is chosen by the slave.  The number can depend on host
> +resource availability or slave implementation details.  Such devices are called
> +multiple queue devices.
> +
>  Multiple queue support allows the slave to advertise the maximum number of
>  queues.  This is treated as a protocol extension, hence the slave has to
>  implement protocol features first. The multiple queues feature is supported
> @@ -339,6 +348,14 @@ queue in the sent message to identify a specified queue.
>  The master enables queues by sending message ``VHOST_USER_SET_VRING_ENABLE``.
>  vhost-user-net has historically automatically enabled the first queue pair.
>  
> +Slaves should always implement the ``VHOST_USER_PROTOCOL_F_MQ`` protocol
> +feature, even for devices with a fixed number of virtqueues, since it is simple
> +to implement and offers a degree of introspection.
> +
> +Masters must not rely on the ``VHOST_USER_PROTOCOL_F_MQ`` protocol feature for
> +devices with a fixed number of virtqueues.  Only true multiqueue devices
> +require this protocol feature.
> +
>  Migration
>  ---------
>  
> -- 
> 2.21.0
> 

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Re: [Qemu-devel] [PATCH] docs: clarify multiqueue vs multiple virtqueues

[Michael S. Tsirkin]

On Wed, Jul 17, 2019 at 11:14:53AM +0100, Stefan Hajnoczi wrote:
> On Mon, Jun 24, 2019 at 10:13:04AM +0100, Stefan Hajnoczi wrote:
> > The vhost-user specification does not explain when
> > VHOST_USER_PROTOCOL_F_MQ must be implemented.  This may lead
> > implementors of vhost-user masters to believe that this protocol feature
> > is required for any device that has multiple virtqueues.  That would be
> > a mistake since existing vhost-user slaves offer multiple virtqueues but
> > do not advertise VHOST_USER_PROTOCOL_F_MQ.
> > 
> > For example, a vhost-net device with one rx/tx queue pair is not
> > multiqueue.  The slave does not need to advertise
> > VHOST_USER_PROTOCOL_F_MQ.  Therefore the master must assume it has these
> > virtqueues and cannot rely on askingt the slave how many virtqueues
> > exist.
> > 
> > Extend the specification to explain the different between true
> > multiqueue and regular devices with a fixed virtqueue layout.
> > 
> > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> > ---
> > Based-on: <20190621094005.4134-1-stefanha@redhat.com>
> > ---
> >  docs/interop/vhost-user.rst | 17 +++++++++++++++++
> >  1 file changed, 17 insertions(+)
> 
> Ping?

queued, thanks!

> > 
> > diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
> > index 5750668aba..7827b710aa 100644
> > --- a/docs/interop/vhost-user.rst
> > +++ b/docs/interop/vhost-user.rst
> > @@ -324,6 +324,15 @@ must support changing some configuration aspects on the fly.
> >  Multiple queue support
> >  ----------------------
> >  
> > +Many devices have a fixed number of virtqueues.  In this case the master
> > +already knows the number of available virtqueues without communicating with the
> > +slave.
> > +
> > +Some devices do not have a fixed number of virtqueues.  Instead the maximum
> > +number of virtqueues is chosen by the slave.  The number can depend on host
> > +resource availability or slave implementation details.  Such devices are called
> > +multiple queue devices.
> > +
> >  Multiple queue support allows the slave to advertise the maximum number of
> >  queues.  This is treated as a protocol extension, hence the slave has to
> >  implement protocol features first. The multiple queues feature is supported
> > @@ -339,6 +348,14 @@ queue in the sent message to identify a specified queue.
> >  The master enables queues by sending message ``VHOST_USER_SET_VRING_ENABLE``.
> >  vhost-user-net has historically automatically enabled the first queue pair.
> >  
> > +Slaves should always implement the ``VHOST_USER_PROTOCOL_F_MQ`` protocol
> > +feature, even for devices with a fixed number of virtqueues, since it is simple
> > +to implement and offers a degree of introspection.
> > +
> > +Masters must not rely on the ``VHOST_USER_PROTOCOL_F_MQ`` protocol feature for
> > +devices with a fixed number of virtqueues.  Only true multiqueue devices
> > +require this protocol feature.
> > +
> >  Migration
> >  ---------
> >  
> > -- 
> > 2.21.0
> > 

[Qemu-devel] [PATCH] ioapic: kvm: Skip route updates for masked pins

[Jan Kiszka]

From: Jan Kiszka <jan.kiszka@siemens.com>

Masked entries will not generate interrupt messages, thus do no need to
be routed by KVM. This is a cosmetic cleanup, just avoiding warnings of
the kind

qemu-system-x86_64: vtd_irte_get: detected non-present IRTE (index=0, high=0xff00, low=0x100)

if the masked entry happens to reference a non-present IRTE.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 hw/intc/ioapic.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c
index 7074489fdf..2fb288a22d 100644
--- a/hw/intc/ioapic.c
+++ b/hw/intc/ioapic.c
@@ -197,9 +197,11 @@ static void ioapic_update_kvm_routes(IOAPICCommonState *s)
             MSIMessage msg;
             struct ioapic_entry_info info;
             ioapic_entry_parse(s->ioredtbl[i], &info);
-            msg.address = info.addr;
-            msg.data = info.data;
-            kvm_irqchip_update_msi_route(kvm_state, i, msg, NULL);
+            if (!info.masked) {
+                msg.address = info.addr;
+                msg.data = info.data;
+                kvm_irqchip_update_msi_route(kvm_state, i, msg, NULL);
+            }
         }
         kvm_irqchip_commit_routes(kvm_state);
     }
-- 
2.16.4

[Qemu-devel] [PULL 03/12] ioapic: kvm: Skip route updates for masked pins

[Michael S. Tsirkin]

From: Jan Kiszka <jan.kiszka@siemens.com>

Masked entries will not generate interrupt messages, thus do no need to
be routed by KVM. This is a cosmetic cleanup, just avoiding warnings of
the kind

qemu-system-x86_64: vtd_irte_get: detected non-present IRTE (index=0, high=0xff00, low=0x100)

if the masked entry happens to reference a non-present IRTE.

Cc: qemu-stable@nongnu.org
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Message-Id: <a84b7e03-f9a8-b577-be27-4d93d1caa1c9@siemens.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
---
 hw/intc/ioapic.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c
index c408749876..e99c37cceb 100644
--- a/hw/intc/ioapic.c
+++ b/hw/intc/ioapic.c
@@ -197,9 +197,11 @@ static void ioapic_update_kvm_routes(IOAPICCommonState *s)
             MSIMessage msg;
             struct ioapic_entry_info info;
             ioapic_entry_parse(s->ioredtbl[i], &info);
-            msg.address = info.addr;
-            msg.data = info.data;
-            kvm_irqchip_update_msi_route(kvm_state, i, msg, NULL);
+            if (!info.masked) {
+                msg.address = info.addr;
+                msg.data = info.data;
+                kvm_irqchip_update_msi_route(kvm_state, i, msg, NULL);
+            }
         }
         kvm_irqchip_commit_routes(kvm_state);
     }
-- 
MST

Re: [Qemu-devel] [PATCH] ioapic: kvm: Skip route updates for masked pins

[Peter Xu]

On Sun, Jun 02, 2019 at 01:42:13PM +0200, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> Masked entries will not generate interrupt messages, thus do no need to
> be routed by KVM. This is a cosmetic cleanup, just avoiding warnings of
> the kind
> 
> qemu-system-x86_64: vtd_irte_get: detected non-present IRTE (index=0, high=0xff00, low=0x100)
> 
> if the masked entry happens to reference a non-present IRTE.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

Reviewed-by: Peter Xu <peterx@redhat.com>

Thanks, Jan.

The "non-cosmetic" part of clearing of those entries (e.g. including
when the entries were not setup correctly rather than masked) was
never really implemented and that task has been on my todo list for
quite a while but with a very low priority (low enough to sink...).  I
hope I didn't overlook its importance since AFAICT general OSs should
hardly trigger those paths and so far I don't see it a very big issue.

Regards,

-- 
Peter Xu

Re: [Qemu-devel] [PATCH] ioapic: kvm: Skip route updates for masked pins

[Jan Kiszka]

On 02.06.19 14:10, Peter Xu wrote:
> On Sun, Jun 02, 2019 at 01:42:13PM +0200, Jan Kiszka wrote:
>> From: Jan Kiszka <jan.kiszka@siemens.com>
>>
>> Masked entries will not generate interrupt messages, thus do no need to
>> be routed by KVM. This is a cosmetic cleanup, just avoiding warnings of
>> the kind
>>
>> qemu-system-x86_64: vtd_irte_get: detected non-present IRTE (index=0, high=0xff00, low=0x100)
>>
>> if the masked entry happens to reference a non-present IRTE.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> 
> Reviewed-by: Peter Xu <peterx@redhat.com>
> 
> Thanks, Jan.
> 
> The "non-cosmetic" part of clearing of those entries (e.g. including
> when the entries were not setup correctly rather than masked) was
> never really implemented and that task has been on my todo list for
> quite a while but with a very low priority (low enough to sink...).  I
> hope I didn't overlook its importance since AFAICT general OSs should
> hardly trigger those paths and so far I don't see it a very big issue.

I triggered the message during the handover phase from Linux to Jailhouse. That 
involves reprogramming both IOAPIC and IRTEs - likely unusual sequences, I just 
didn't find invalid ones.

Thanks,
Jan

-- 
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux

Re: [Qemu-devel] [PATCH] ioapic: kvm: Skip route updates for masked pins

[Michael S. Tsirkin]

On Sun, Jun 02, 2019 at 01:42:13PM +0200, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> Masked entries will not generate interrupt messages, thus do no need to
> be routed by KVM. This is a cosmetic cleanup, just avoiding warnings of
> the kind
> 
> qemu-system-x86_64: vtd_irte_get: detected non-present IRTE (index=0, high=0xff00, low=0x100)
> 
> if the masked entry happens to reference a non-present IRTE.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  hw/intc/ioapic.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c
> index 7074489fdf..2fb288a22d 100644
> --- a/hw/intc/ioapic.c
> +++ b/hw/intc/ioapic.c
> @@ -197,9 +197,11 @@ static void ioapic_update_kvm_routes(IOAPICCommonState *s)
>              MSIMessage msg;
>              struct ioapic_entry_info info;
>              ioapic_entry_parse(s->ioredtbl[i], &info);
> -            msg.address = info.addr;
> -            msg.data = info.data;
> -            kvm_irqchip_update_msi_route(kvm_state, i, msg, NULL);
> +            if (!info.masked) {
> +                msg.address = info.addr;
> +                msg.data = info.data;
> +                kvm_irqchip_update_msi_route(kvm_state, i, msg, NULL);
> +            }
>          }
>          kvm_irqchip_commit_routes(kvm_state);
>      }
> -- 
> 2.16.4

Re: [Qemu-devel] [PATCH] ioapic: kvm: Skip route updates for masked pins

[Jan Kiszka]

On 03.06.19 02:36, Michael S. Tsirkin wrote:
> On Sun, Jun 02, 2019 at 01:42:13PM +0200, Jan Kiszka wrote:
>> From: Jan Kiszka <jan.kiszka@siemens.com>
>>
>> Masked entries will not generate interrupt messages, thus do no need to
>> be routed by KVM. This is a cosmetic cleanup, just avoiding warnings of
>> the kind
>>
>> qemu-system-x86_64: vtd_irte_get: detected non-present IRTE (index=0, high=0xff00, low=0x100)
>>
>> if the masked entry happens to reference a non-present IRTE.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
>
>> ---
>>  hw/intc/ioapic.c | 8 +++++---
>>  1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c
>> index 7074489fdf..2fb288a22d 100644
>> --- a/hw/intc/ioapic.c
>> +++ b/hw/intc/ioapic.c
>> @@ -197,9 +197,11 @@ static void ioapic_update_kvm_routes(IOAPICCommonState *s)
>>              MSIMessage msg;
>>              struct ioapic_entry_info info;
>>              ioapic_entry_parse(s->ioredtbl[i], &info);
>> -            msg.address = info.addr;
>> -            msg.data = info.data;
>> -            kvm_irqchip_update_msi_route(kvm_state, i, msg, NULL);
>> +            if (!info.masked) {
>> +                msg.address = info.addr;
>> +                msg.data = info.data;
>> +                kvm_irqchip_update_msi_route(kvm_state, i, msg, NULL);
>> +            }
>>          }
>>          kvm_irqchip_commit_routes(kvm_state);
>>      }
>> --
>> 2.16.4
>
>

Ping. Or is this queued for 4.2?

Jan

Re: [Qemu-devel] [PATCH] ioapic: kvm: Skip route updates for masked pins

[Michael S. Tsirkin]

On Sun, Jul 21, 2019 at 10:58:42AM +0200, Jan Kiszka wrote:
> On 03.06.19 02:36, Michael S. Tsirkin wrote:
> > On Sun, Jun 02, 2019 at 01:42:13PM +0200, Jan Kiszka wrote:
> >> From: Jan Kiszka <jan.kiszka@siemens.com>
> >>
> >> Masked entries will not generate interrupt messages, thus do no need to
> >> be routed by KVM. This is a cosmetic cleanup, just avoiding warnings of
> >> the kind
> >>
> >> qemu-system-x86_64: vtd_irte_get: detected non-present IRTE (index=0, high=0xff00, low=0x100)
> >>
> >> if the masked entry happens to reference a non-present IRTE.
> >>
> >> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> >
> > Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> >
> >> ---
> >>  hw/intc/ioapic.c | 8 +++++---
> >>  1 file changed, 5 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c
> >> index 7074489fdf..2fb288a22d 100644
> >> --- a/hw/intc/ioapic.c
> >> +++ b/hw/intc/ioapic.c
> >> @@ -197,9 +197,11 @@ static void ioapic_update_kvm_routes(IOAPICCommonState *s)
> >>              MSIMessage msg;
> >>              struct ioapic_entry_info info;
> >>              ioapic_entry_parse(s->ioredtbl[i], &info);
> >> -            msg.address = info.addr;
> >> -            msg.data = info.data;
> >> -            kvm_irqchip_update_msi_route(kvm_state, i, msg, NULL);
> >> +            if (!info.masked) {
> >> +                msg.address = info.addr;
> >> +                msg.data = info.data;
> >> +                kvm_irqchip_update_msi_route(kvm_state, i, msg, NULL);
> >> +            }
> >>          }
> >>          kvm_irqchip_commit_routes(kvm_state);
> >>      }
> >> --
> >> 2.16.4
> >
> >
> 
> Ping. Or is this queued for 4.2?
> 
> Jan

Paolo was queueing ioapic things recently. I can take this if
he doesn't respond until I pack up my next pull req.

-- 
MST

Re: [Qemu-devel] [PATCH] ioapic: kvm: Skip route updates for masked pins

[Paolo Bonzini]

On 21/07/19 12:04, Michael S. Tsirkin wrote:
> On Sun, Jul 21, 2019 at 10:58:42AM +0200, Jan Kiszka wrote:
>> On 03.06.19 02:36, Michael S. Tsirkin wrote:
>>> On Sun, Jun 02, 2019 at 01:42:13PM +0200, Jan Kiszka wrote:
>>>> From: Jan Kiszka <jan.kiszka@siemens.com>
>>>>
>>>> Masked entries will not generate interrupt messages, thus do no need to
>>>> be routed by KVM. This is a cosmetic cleanup, just avoiding warnings of
>>>> the kind
>>>>
>>>> qemu-system-x86_64: vtd_irte_get: detected non-present IRTE (index=0, high=0xff00, low=0x100)
>>>>
>>>> if the masked entry happens to reference a non-present IRTE.
>>>>
>>>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>>>
>>> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
>>>
>>>> ---
>>>>  hw/intc/ioapic.c | 8 +++++---
>>>>  1 file changed, 5 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c
>>>> index 7074489fdf..2fb288a22d 100644
>>>> --- a/hw/intc/ioapic.c
>>>> +++ b/hw/intc/ioapic.c
>>>> @@ -197,9 +197,11 @@ static void ioapic_update_kvm_routes(IOAPICCommonState *s)
>>>>              MSIMessage msg;
>>>>              struct ioapic_entry_info info;
>>>>              ioapic_entry_parse(s->ioredtbl[i], &info);
>>>> -            msg.address = info.addr;
>>>> -            msg.data = info.data;
>>>> -            kvm_irqchip_update_msi_route(kvm_state, i, msg, NULL);
>>>> +            if (!info.masked) {
>>>> +                msg.address = info.addr;
>>>> +                msg.data = info.data;
>>>> +                kvm_irqchip_update_msi_route(kvm_state, i, msg, NULL);
>>>> +            }
>>>>          }
>>>>          kvm_irqchip_commit_routes(kvm_state);
>>>>      }
>>>> --
>>>> 2.16.4
>>>
>>>
>>
>> Ping. Or is this queued for 4.2?
>>
>> Jan
> 
> Paolo was queueing ioapic things recently. I can take this if
> he doesn't respond until I pack up my next pull req.
> 

I've already sent a pull request and had missed this patch, so please go
ahead.

Paolo