* [PATCH] virtiofs: Relax DAX window protection for ppc
@ 2019-12-02 20:26 Fabiano Rosas
2019-12-03 10:07 ` Dr. David Alan Gilbert
0 siblings, 1 reply; 2+ messages in thread
From: Fabiano Rosas @ 2019-12-02 20:26 UTC (permalink / raw)
To: virtio-fs; +Cc: qemu-ppc, qemu-devel, stefanha, dgilbert
When setting up the DAX window during the virtiofs driver probe inside
the guest, the Linux arch-specific function arch_add_memory is called,
which on ppc tries to do a cache flush [1] of the recently added
memory. At this point the window is mmap'ed PROT_NONE by QEMU, which
causes the following:
<snip>
[ 10.136703] virtio_fs virtio0: Cache len: 0x80000000 @ 0x210000000000
[ 10.165106] radix-mmu: Mapped 0xc000210000000000-0xc000210080000000 with 1.00 GiB pages
error: kvm run failed Bad address
NIP c000000000072350 LR c000000000072304 CTR 0000000001000000 XER 0000000020040000 CPU#0
MSR 8000000002009033 HID0 0000000000000000 HF 8000000000000000 iidx 3 didx 3
TB 00000000 00000000 DECR 0
GPR00 c000000000072304 c0000000fa383100 c000000001190300 0000000000000000
GPR04 0000000000000001 0000000000000000 c0000000fa383208 0000000000000080
GPR08 c000210000000000 000000008000007f 0000000001000000 6874697720303030
<snip>
The problem is the same for the memory device removal path
(e.g. during filesystem unmount).
Since powerpc expects the memory to be accessible during device
addition/removal, this patch makes the DAX window readable at creation
and after virtio-fs unmap.
1 - https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fb5924fd
Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
---
hw/virtio/vhost-user-fs.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/hw/virtio/vhost-user-fs.c b/hw/virtio/vhost-user-fs.c
index 455e97beea..92958797d0 100644
--- a/hw/virtio/vhost-user-fs.c
+++ b/hw/virtio/vhost-user-fs.c
@@ -24,6 +24,16 @@
#include "exec/address-spaces.h"
#include "trace.h"
+/*
+ * The powerpc kernel code expects the memory to be accessible during
+ * addition/removal.
+ */
+#if defined(TARGET_PPC64) && defined(CONFIG_LINUX)
+#define DAX_WINDOW_PROT PROT_READ
+#else
+#define DAX_WINDOW_PROT PROT_NONE
+#endif
+
uint64_t vhost_user_fs_slave_map(struct vhost_dev *dev, VhostUserFSSlaveMsg *sm,
int fd)
{
@@ -133,8 +143,8 @@ uint64_t vhost_user_fs_slave_unmap(struct vhost_dev *dev, VhostUserFSSlaveMsg *s
continue;
}
- ptr = mmap(cache_host + sm->c_offset[i], sm->len[i],
- PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+ ptr = mmap(cache_host + sm->c_offset[i], sm->len[i], DAX_WINDOW_PROT,
+ MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
if (ptr != (cache_host + sm->c_offset[i])) {
res = -errno;
fprintf(stderr, "%s: mmap failed (%s) [%d] %"
@@ -485,8 +495,9 @@ static void vuf_device_realize(DeviceState *dev, Error **errp)
if (fs->conf.cache_size) {
/* Anonymous, private memory is not counted as overcommit */
- cache_ptr = mmap(NULL, fs->conf.cache_size, PROT_NONE,
+ cache_ptr = mmap(NULL, fs->conf.cache_size, DAX_WINDOW_PROT,
MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+
if (cache_ptr == MAP_FAILED) {
error_setg(errp, "Unable to mmap blank cache");
return;
--
2.23.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] virtiofs: Relax DAX window protection for ppc
2019-12-02 20:26 [PATCH] virtiofs: Relax DAX window protection for ppc Fabiano Rosas
@ 2019-12-03 10:07 ` Dr. David Alan Gilbert
0 siblings, 0 replies; 2+ messages in thread
From: Dr. David Alan Gilbert @ 2019-12-03 10:07 UTC (permalink / raw)
To: Fabiano Rosas; +Cc: virtio-fs, qemu-ppc, qemu-devel, stefanha
* Fabiano Rosas (farosas@linux.ibm.com) wrote:
> When setting up the DAX window during the virtiofs driver probe inside
> the guest, the Linux arch-specific function arch_add_memory is called,
> which on ppc tries to do a cache flush [1] of the recently added
> memory. At this point the window is mmap'ed PROT_NONE by QEMU, which
> causes the following:
>
> <snip>
> [ 10.136703] virtio_fs virtio0: Cache len: 0x80000000 @ 0x210000000000
> [ 10.165106] radix-mmu: Mapped 0xc000210000000000-0xc000210080000000 with 1.00 GiB pages
> error: kvm run failed Bad address
> NIP c000000000072350 LR c000000000072304 CTR 0000000001000000 XER 0000000020040000 CPU#0
> MSR 8000000002009033 HID0 0000000000000000 HF 8000000000000000 iidx 3 didx 3
> TB 00000000 00000000 DECR 0
> GPR00 c000000000072304 c0000000fa383100 c000000001190300 0000000000000000
> GPR04 0000000000000001 0000000000000000 c0000000fa383208 0000000000000080
> GPR08 c000210000000000 000000008000007f 0000000001000000 6874697720303030
> <snip>
>
> The problem is the same for the memory device removal path
> (e.g. during filesystem unmount).
>
> Since powerpc expects the memory to be accessible during device
> addition/removal, this patch makes the DAX window readable at creation
> and after virtio-fs unmap.
>
> 1 - https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fb5924fd
>
> Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Thanks, I'll do a pull after the tree opens again.
Dave
> ---
> hw/virtio/vhost-user-fs.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/hw/virtio/vhost-user-fs.c b/hw/virtio/vhost-user-fs.c
> index 455e97beea..92958797d0 100644
> --- a/hw/virtio/vhost-user-fs.c
> +++ b/hw/virtio/vhost-user-fs.c
> @@ -24,6 +24,16 @@
> #include "exec/address-spaces.h"
> #include "trace.h"
>
> +/*
> + * The powerpc kernel code expects the memory to be accessible during
> + * addition/removal.
> + */
> +#if defined(TARGET_PPC64) && defined(CONFIG_LINUX)
> +#define DAX_WINDOW_PROT PROT_READ
> +#else
> +#define DAX_WINDOW_PROT PROT_NONE
> +#endif
> +
> uint64_t vhost_user_fs_slave_map(struct vhost_dev *dev, VhostUserFSSlaveMsg *sm,
> int fd)
> {
> @@ -133,8 +143,8 @@ uint64_t vhost_user_fs_slave_unmap(struct vhost_dev *dev, VhostUserFSSlaveMsg *s
> continue;
> }
>
> - ptr = mmap(cache_host + sm->c_offset[i], sm->len[i],
> - PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
> + ptr = mmap(cache_host + sm->c_offset[i], sm->len[i], DAX_WINDOW_PROT,
> + MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
> if (ptr != (cache_host + sm->c_offset[i])) {
> res = -errno;
> fprintf(stderr, "%s: mmap failed (%s) [%d] %"
> @@ -485,8 +495,9 @@ static void vuf_device_realize(DeviceState *dev, Error **errp)
>
> if (fs->conf.cache_size) {
> /* Anonymous, private memory is not counted as overcommit */
> - cache_ptr = mmap(NULL, fs->conf.cache_size, PROT_NONE,
> + cache_ptr = mmap(NULL, fs->conf.cache_size, DAX_WINDOW_PROT,
> MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
> +
> if (cache_ptr == MAP_FAILED) {
> error_setg(errp, "Unable to mmap blank cache");
> return;
> --
> 2.23.0
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
^ permalink raw reply [flat|nested] 2+ messages in thread
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