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From: Alexander Duyck <alexander.duyck@gmail.com>
To: nitesh@redhat.com, kvm@vger.kernel.org, david@redhat.com,
	mst@redhat.com, dave.hansen@intel.com,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	akpm@linux-foundation.org
Cc: yang.zhang.wz@gmail.com, pagupta@redhat.com, riel@surriel.com,
	konrad.wilk@oracle.com, willy@infradead.org,
	lcapitulino@redhat.com, wei.w.wang@intel.com,
	aarcange@redhat.com, pbonzini@redhat.com,
	dan.j.williams@intel.com, alexander.h.duyck@linux.intel.com
Subject: [PATCH v4 QEMU 1/3] virtio-ballon: Implement support for page poison tracking feature
Date: Wed, 07 Aug 2019 15:43:11 -0700	[thread overview]
Message-ID: <20190807224311.7333.70569.stgit@localhost.localdomain> (raw)
In-Reply-To: <20190807224037.6891.53512.stgit@localhost.localdomain>

From: Alexander Duyck <alexander.h.duyck@linux.intel.com>

We need to make certain to advertise support for page poison tracking if
we want to actually get data on if the guest will be poisoning pages. So
if free page hinting is active we should add page poisoning support and
let the guest disable it if it isn't using it.

Page poisoning will result in a page being dirtied on free. As such we
cannot really avoid having to copy the page at least one more time since
we will need to write the poison value to the destination. As such we can
just ignore free page hinting if page poisoning is enabled as it will
actually reduce the work we have to do.

Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
 hw/virtio/virtio-balloon.c         |   25 +++++++++++++++++++++----
 include/hw/virtio/virtio-balloon.h |    1 +
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 25de15430710..003b3ebcfdfb 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -530,6 +530,15 @@ static void virtio_balloon_free_page_start(VirtIOBalloon *s)
         return;
     }
 
+    /*
+     * If page poisoning is enabled then we probably shouldn't bother with
+     * the hinting since the poisoning will dirty the page and invalidate
+     * the work we are doing anyway.
+     */
+    if (virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
+        return;
+    }
+
     if (s->free_page_report_cmd_id == UINT_MAX) {
         s->free_page_report_cmd_id =
                        VIRTIO_BALLOON_FREE_PAGE_REPORT_CMD_ID_MIN;
@@ -617,12 +626,10 @@ static size_t virtio_balloon_config_size(VirtIOBalloon *s)
     if (s->qemu_4_0_config_size) {
         return sizeof(struct virtio_balloon_config);
     }
-    if (virtio_has_feature(features, VIRTIO_BALLOON_F_PAGE_POISON)) {
+    if (virtio_has_feature(features, VIRTIO_BALLOON_F_PAGE_POISON) ||
+        virtio_has_feature(features, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
         return sizeof(struct virtio_balloon_config);
     }
-    if (virtio_has_feature(features, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
-        return offsetof(struct virtio_balloon_config, poison_val);
-    }
     return offsetof(struct virtio_balloon_config, free_page_report_cmd_id);
 }
 
@@ -633,6 +640,7 @@ static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
 
     config.num_pages = cpu_to_le32(dev->num_pages);
     config.actual = cpu_to_le32(dev->actual);
+    config.poison_val = cpu_to_le32(dev->poison_val);
 
     if (dev->free_page_report_status == FREE_PAGE_REPORT_S_REQUESTED) {
         config.free_page_report_cmd_id =
@@ -696,6 +704,8 @@ static void virtio_balloon_set_config(VirtIODevice *vdev,
         qapi_event_send_balloon_change(vm_ram_size -
                         ((ram_addr_t) dev->actual << VIRTIO_BALLOON_PFN_SHIFT));
     }
+    dev->poison_val = virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON) ? 
+                      le32_to_cpu(config.poison_val) : 0;
     trace_virtio_balloon_set_config(dev->actual, oldactual);
 }
 
@@ -705,6 +715,9 @@ static uint64_t virtio_balloon_get_features(VirtIODevice *vdev, uint64_t f,
     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
     f |= dev->host_features;
     virtio_add_feature(&f, VIRTIO_BALLOON_F_STATS_VQ);
+    if (virtio_has_feature(f, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
+        virtio_add_feature(&f, VIRTIO_BALLOON_F_PAGE_POISON);
+    }
 
     return f;
 }
@@ -846,6 +859,8 @@ static void virtio_balloon_device_reset(VirtIODevice *vdev)
         g_free(s->stats_vq_elem);
         s->stats_vq_elem = NULL;
     }
+
+    s->poison_val = 0;
 }
 
 static void virtio_balloon_set_status(VirtIODevice *vdev, uint8_t status)
@@ -908,6 +923,8 @@ static Property virtio_balloon_properties[] = {
                     VIRTIO_BALLOON_F_DEFLATE_ON_OOM, false),
     DEFINE_PROP_BIT("free-page-hint", VirtIOBalloon, host_features,
                     VIRTIO_BALLOON_F_FREE_PAGE_HINT, false),
+    DEFINE_PROP_BIT("x-page-poison", VirtIOBalloon, host_features,
+                    VIRTIO_BALLOON_F_PAGE_POISON, false),
     /* QEMU 4.0 accidentally changed the config size even when free-page-hint
      * is disabled, resulting in QEMU 3.1 migration incompatibility.  This
      * property retains this quirk for QEMU 4.1 machine types.
diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h
index d1c968d2376e..7fe78e5c14d7 100644
--- a/include/hw/virtio/virtio-balloon.h
+++ b/include/hw/virtio/virtio-balloon.h
@@ -70,6 +70,7 @@ typedef struct VirtIOBalloon {
     uint32_t host_features;
 
     bool qemu_4_0_config_size;
+    uint32_t poison_val;
 } VirtIOBalloon;
 
 #endif


  parent reply	other threads:[~2019-08-07 22:43 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-07 22:41 [PATCH v4 0/6] mm / virtio: Provide support for unused page reporting Alexander Duyck
2019-08-07 22:41 ` [PATCH v4 1/6] mm: Adjust shuffle code to allow for future coalescing Alexander Duyck
2019-08-07 22:41 ` [PATCH v4 2/6] mm: Move set/get_pcppage_migratetype to mmzone.h Alexander Duyck
2019-08-07 22:42 ` [PATCH v4 3/6] mm: Use zone and order instead of free area in free_list manipulators Alexander Duyck
2019-08-07 22:42 ` [PATCH v4 4/6] mm: Introduce Reported pages Alexander Duyck
2019-08-08 13:45   ` Nitesh Narayan Lal
2019-08-08 15:11     ` Alexander Duyck
2019-08-07 22:42 ` [PATCH v4 5/6] virtio-balloon: Pull page poisoning config out of free page hinting Alexander Duyck
2019-08-07 22:42 ` [PATCH v4 6/6] virtio-balloon: Add support for providing unused page reports to host Alexander Duyck
2019-08-12  9:53   ` Michael S. Tsirkin
2019-08-12 15:20     ` Alexander Duyck
2019-08-12 15:43       ` Michael S. Tsirkin
2019-08-12 15:49       ` David Hildenbrand
2019-08-12 16:09         ` Alexander Duyck
2019-08-07 22:43 ` Alexander Duyck [this message]
2019-08-07 22:43 ` [PATCH v4 QEMU 2/3] virtio-balloon: Add bit to notify guest of unused page reporting Alexander Duyck
2019-08-07 22:43 ` [PATCH v4 QEMU 3/3] virtio-balloon: Provide a interface for " Alexander Duyck

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