* [PATCH v1 0/1] Don't split flush for amd_iommu_domain_flush_all()
@ 2026-04-14 21:06 Weinan Liu
2026-04-14 21:06 ` [PATCH v1 1/1] iommu/amd: " Weinan Liu
0 siblings, 1 reply; 6+ messages in thread
From: Weinan Liu @ 2026-04-14 21:06 UTC (permalink / raw)
To: iommu, jgg
Cc: joro, patches, robin.murphy, suravee.suthikulpanit, wei.w.wang,
will, kpsingh, josef, Weinan Liu
This patch is a respin of Josef Bacik's original work[1] to fix the
performance issues and soft lockups in the AMD IOMMU driver when running
within a VM. I am taking over the respin as Josef currently has limited
time for this
[1]:https://lore.kernel.org/linux-iommu/ad8652c5e9f8aeee05e2103f4987589cdd4a3fd0.1772659768.git.josef@toxicpanda.com
Weinan Liu (1):
iommu/amd: Don't split flush for amd_iommu_domain_flush_all()
drivers/iommu/amd/iommu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--
2.54.0.rc0.605.g598a273b03-goog
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v1 1/1] iommu/amd: Don't split flush for amd_iommu_domain_flush_all()
2026-04-14 21:06 [PATCH v1 0/1] Don't split flush for amd_iommu_domain_flush_all() Weinan Liu
@ 2026-04-14 21:06 ` Weinan Liu
2026-04-14 23:36 ` Jason Gunthorpe
2026-04-14 23:55 ` Samiullah Khawaja
0 siblings, 2 replies; 6+ messages in thread
From: Weinan Liu @ 2026-04-14 21:06 UTC (permalink / raw)
To: iommu, jgg
Cc: joro, patches, robin.murphy, suravee.suthikulpanit, wei.w.wang,
will, kpsingh, josef, Weinan Liu
We have observed multiple full invalidations occurring during device
detach when we are done using the vfio-device.
blocked_domain_attach_device()
-> detach_device()
-> amd_iommu_domain_flush_all()
-> amd_iommu_domain_flush_pages(..., CMD_INV_IOMMU_ALL_PAGES_ADDRESS)
while (size != 0) {
-> __domain_flush_pages( flush_size /* power of 2 flush_size */)
-> domain_flush_pages_v1()
-> build_inv_iommu_pages()
-> build_inv_address()
}
build_inv_address() will trigger a full invalidation if the chunk
size > (1 << 51). Consequently, the guest will issue multiple full
invalidations for a single call to amd_iommu_domain_flush_all()
Without this patch, we will see 10 time instead of 1 time full
invalidations for every amd_iommu_domain_flush_all().
Fixes: a270be1b3fdf ("iommu/amd: Use only natural aligned flushes in a VM")
Suggested-by: Josef Bacik <josef@toxicpanda.com>
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Weinan Liu <wnliu@google.com>
---
drivers/iommu/amd/iommu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 760d5f4623b5..bcec8721d228 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1769,7 +1769,8 @@ void amd_iommu_domain_flush_pages(struct protection_domain *domain,
{
lockdep_assert_held(&domain->lock);
- if (likely(!amd_iommu_np_cache)) {
+ if (likely(!amd_iommu_np_cache) ||
+ size == CMD_INV_IOMMU_ALL_PAGES_ADDRESS) {
__domain_flush_pages(domain, address, size);
/* Wait until IOMMU TLB and all device IOTLB flushes are complete */
--
2.54.0.rc0.605.g598a273b03-goog
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH v1 1/1] iommu/amd: Don't split flush for amd_iommu_domain_flush_all()
2026-04-14 21:06 ` [PATCH v1 1/1] iommu/amd: " Weinan Liu
@ 2026-04-14 23:36 ` Jason Gunthorpe
2026-04-15 0:30 ` Weinan Liu
2026-04-14 23:55 ` Samiullah Khawaja
1 sibling, 1 reply; 6+ messages in thread
From: Jason Gunthorpe @ 2026-04-14 23:36 UTC (permalink / raw)
To: Weinan Liu
Cc: iommu, joro, patches, robin.murphy, suravee.suthikulpanit,
wei.w.wang, will, kpsingh, josef
On Tue, Apr 14, 2026 at 09:06:26PM +0000, Weinan Liu wrote:
> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> index 760d5f4623b5..bcec8721d228 100644
> --- a/drivers/iommu/amd/iommu.c
> +++ b/drivers/iommu/amd/iommu.c
> @@ -1769,7 +1769,8 @@ void amd_iommu_domain_flush_pages(struct protection_domain *domain,
> {
> lockdep_assert_held(&domain->lock);
>
> - if (likely(!amd_iommu_np_cache)) {
> + if (likely(!amd_iommu_np_cache) ||
> + size == CMD_INV_IOMMU_ALL_PAGES_ADDRESS) {
This is better as size >= (1ULL<<52)
Which is the break point where it switches over to full invalidation
anyhow, there is no sense then in doing the special np flow..
Otherwise
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Jason
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH v1 1/1] iommu/amd: Don't split flush for amd_iommu_domain_flush_all()
2026-04-14 23:36 ` Jason Gunthorpe
@ 2026-04-15 0:30 ` Weinan Liu
2026-04-17 11:57 ` Jason Gunthorpe
0 siblings, 1 reply; 6+ messages in thread
From: Weinan Liu @ 2026-04-15 0:30 UTC (permalink / raw)
To: jgg
Cc: iommu, joro, josef, kpsingh, patches, robin.murphy,
suravee.suthikulpanit, wei.w.wang, will, wnliu
We have observed multiple full invalidations occurring during device
detach when we are done using the vfio-device.
blocked_domain_attach_device()
-> detach_device()
-> amd_iommu_domain_flush_all()
-> amd_iommu_domain_flush_pages(..., CMD_INV_IOMMU_ALL_PAGES_ADDRESS)
while (size != 0) {
-> __domain_flush_pages( flush_size /* power of 2 flush_size */)
-> domain_flush_pages_v1()
-> build_inv_iommu_pages()
-> build_inv_address()
}
build_inv_address() will trigger a full invalidation if the chunk
size > (1 << 51). Consequently, the guest will issue multiple full
invalidations for a single call to amd_iommu_domain_flush_all()
Without this patch, we will see 10 time instead of 1 time full
invalidations for every amd_iommu_domain_flush_all().
Fixes: a270be1b3fdf ("iommu/amd: Use only natural aligned flushes in a VM")
Suggested-by: Josef Bacik <josef@toxicpanda.com>
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Weinan Liu <wnliu@google.com>
---
drivers/iommu/amd/iommu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 760d5f4623b5..59650a44ab50 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1769,7 +1769,8 @@ void amd_iommu_domain_flush_pages(struct protection_domain *domain,
{
lockdep_assert_held(&domain->lock);
- if (likely(!amd_iommu_np_cache)) {
+ if (likely(!amd_iommu_np_cache) ||
+ size >= (1ULL<<52)) {
__domain_flush_pages(domain, address, size);
/* Wait until IOMMU TLB and all device IOTLB flushes are complete */
--
2.54.0.rc0.605.g598a273b03-goog
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH v1 1/1] iommu/amd: Don't split flush for amd_iommu_domain_flush_all()
2026-04-15 0:30 ` Weinan Liu
@ 2026-04-17 11:57 ` Jason Gunthorpe
0 siblings, 0 replies; 6+ messages in thread
From: Jason Gunthorpe @ 2026-04-17 11:57 UTC (permalink / raw)
To: Weinan Liu
Cc: iommu, joro, josef, kpsingh, patches, robin.murphy,
suravee.suthikulpanit, wei.w.wang, will
On Wed, Apr 15, 2026 at 12:30:46AM +0000, Weinan Liu wrote:
> We have observed multiple full invalidations occurring during device
> detach when we are done using the vfio-device.
>
> blocked_domain_attach_device()
> -> detach_device()
> -> amd_iommu_domain_flush_all()
> -> amd_iommu_domain_flush_pages(..., CMD_INV_IOMMU_ALL_PAGES_ADDRESS)
>
> while (size != 0) {
>
> -> __domain_flush_pages( flush_size /* power of 2 flush_size */)
> -> domain_flush_pages_v1()
> -> build_inv_iommu_pages()
> -> build_inv_address()
>
> }
>
> build_inv_address() will trigger a full invalidation if the chunk
> size > (1 << 51). Consequently, the guest will issue multiple full
> invalidations for a single call to amd_iommu_domain_flush_all()
>
> Without this patch, we will see 10 time instead of 1 time full
> invalidations for every amd_iommu_domain_flush_all().
>
> Fixes: a270be1b3fdf ("iommu/amd: Use only natural aligned flushes in a VM")
>
> Suggested-by: Josef Bacik <josef@toxicpanda.com>
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Weinan Liu <wnliu@google.com>
> ---
> drivers/iommu/amd/iommu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Jason
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v1 1/1] iommu/amd: Don't split flush for amd_iommu_domain_flush_all()
2026-04-14 21:06 ` [PATCH v1 1/1] iommu/amd: " Weinan Liu
2026-04-14 23:36 ` Jason Gunthorpe
@ 2026-04-14 23:55 ` Samiullah Khawaja
1 sibling, 0 replies; 6+ messages in thread
From: Samiullah Khawaja @ 2026-04-14 23:55 UTC (permalink / raw)
To: Weinan Liu
Cc: iommu, jgg, joro, patches, robin.murphy, suravee.suthikulpanit,
wei.w.wang, will, kpsingh, josef
On Tue, Apr 14, 2026 at 09:06:26PM +0000, Weinan Liu wrote:
>We have observed multiple full invalidations occurring during device
>detach when we are done using the vfio-device.
>
>blocked_domain_attach_device()
> -> detach_device()
> -> amd_iommu_domain_flush_all()
> -> amd_iommu_domain_flush_pages(..., CMD_INV_IOMMU_ALL_PAGES_ADDRESS)
>
> while (size != 0) {
>
> -> __domain_flush_pages( flush_size /* power of 2 flush_size */)
> -> domain_flush_pages_v1()
> -> build_inv_iommu_pages()
> -> build_inv_address()
>
> }
>
>build_inv_address() will trigger a full invalidation if the chunk
>size > (1 << 51). Consequently, the guest will issue multiple full
>invalidations for a single call to amd_iommu_domain_flush_all()
>
>Without this patch, we will see 10 time instead of 1 time full
>invalidations for every amd_iommu_domain_flush_all().
>
>Fixes: a270be1b3fdf ("iommu/amd: Use only natural aligned flushes in a VM")
>
>Suggested-by: Josef Bacik <josef@toxicpanda.com>
>Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
>Signed-off-by: Weinan Liu <wnliu@google.com>
>---
> drivers/iommu/amd/iommu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
>index 760d5f4623b5..bcec8721d228 100644
>--- a/drivers/iommu/amd/iommu.c
>+++ b/drivers/iommu/amd/iommu.c
>@@ -1769,7 +1769,8 @@ void amd_iommu_domain_flush_pages(struct protection_domain *domain,
> {
> lockdep_assert_held(&domain->lock);
>
>- if (likely(!amd_iommu_np_cache)) {
>+ if (likely(!amd_iommu_np_cache) ||
>+ size == CMD_INV_IOMMU_ALL_PAGES_ADDRESS) {
> __domain_flush_pages(domain, address, size);
>
> /* Wait until IOMMU TLB and all device IOTLB flushes are complete */
>--
>2.54.0.rc0.605.g598a273b03-goog
>
>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
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2026-04-14 21:06 [PATCH v1 0/1] Don't split flush for amd_iommu_domain_flush_all() Weinan Liu
2026-04-14 21:06 ` [PATCH v1 1/1] iommu/amd: " Weinan Liu
2026-04-14 23:36 ` Jason Gunthorpe
2026-04-15 0:30 ` Weinan Liu
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