* [PATCH 1/1] iommu: Avoid unnecessary cache invalidations
@ 2023-10-26 8:49 Lu Baolu
2023-10-27 4:30 ` Henry Willard
2023-10-27 6:57 ` Joerg Roedel
0 siblings, 2 replies; 3+ messages in thread
From: Lu Baolu @ 2023-10-26 8:49 UTC (permalink / raw)
To: Joerg Roedel
Cc: Will Deacon, Robin Murphy, Jason Gunthorpe, Kevin Tian, iommu,
linux-kernel, Lu Baolu
The iommu_create_device_direct_mappings() only needs to flush the caches
when the mappings are changed in the affected domain. This is not true
for non-DMA domains, or for devices attached to the domain that have no
reserved regions. To avoid unnecessary cache invalidations, add a check
before iommu_flush_iotlb_all().
Fixes: a48ce36e2786 ("iommu: Prevent RESV_DIRECT devices from blocking domains")
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/iommu/iommu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 00d0a2b5d7dc..0cb676590bfa 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1114,7 +1114,8 @@ static int iommu_create_device_direct_mappings(struct iommu_domain *domain,
}
- iommu_flush_iotlb_all(domain);
+ if (!list_empty(&mappings) && iommu_is_dma_domain(domain))
+ iommu_flush_iotlb_all(domain);
out:
iommu_put_resv_regions(dev, &mappings);
--
2.34.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH 1/1] iommu: Avoid unnecessary cache invalidations
2023-10-26 8:49 [PATCH 1/1] iommu: Avoid unnecessary cache invalidations Lu Baolu
@ 2023-10-27 4:30 ` Henry Willard
2023-10-27 6:57 ` Joerg Roedel
1 sibling, 0 replies; 3+ messages in thread
From: Henry Willard @ 2023-10-27 4:30 UTC (permalink / raw)
To: Lu Baolu
Cc: Joerg Roedel, Will Deacon, Robin Murphy, Jason Gunthorpe,
Kevin Tian, iommu@lists.linux.dev, linux-kernel@vger.kernel.org
On Oct 26, 2023, at 1:49 AM, Lu Baolu <baolu.lu@linux.intel.com> wrote:
>
> The iommu_create_device_direct_mappings() only needs to flush the caches
> when the mappings are changed in the affected domain. This is not true
> for non-DMA domains, or for devices attached to the domain that have no
> reserved regions. To avoid unnecessary cache invalidations, add a check
> before iommu_flush_iotlb_all().
This also fixes a boot failure on Sapphire Rapids built with
CONFIG_IOMMU_DEFAULT_PASSTHROUGH=y or the equivalent via
kernel command line parameters.
>
> Fixes: a48ce36e2786 ("iommu: Prevent RESV_DIRECT devices from blocking domains")
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: Henry Willard <henry.willard@oracle.com>
> ---
> drivers/iommu/iommu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 00d0a2b5d7dc..0cb676590bfa 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1114,7 +1114,8 @@ static int iommu_create_device_direct_mappings(struct iommu_domain *domain,
>
> }
>
> - iommu_flush_iotlb_all(domain);
> + if (!list_empty(&mappings) && iommu_is_dma_domain(domain))
> + iommu_flush_iotlb_all(domain);
>
> out:
> iommu_put_resv_regions(dev, &mappings);
> --
> 2.34.1
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH 1/1] iommu: Avoid unnecessary cache invalidations
2023-10-26 8:49 [PATCH 1/1] iommu: Avoid unnecessary cache invalidations Lu Baolu
2023-10-27 4:30 ` Henry Willard
@ 2023-10-27 6:57 ` Joerg Roedel
1 sibling, 0 replies; 3+ messages in thread
From: Joerg Roedel @ 2023-10-27 6:57 UTC (permalink / raw)
To: Lu Baolu
Cc: Will Deacon, Robin Murphy, Jason Gunthorpe, Kevin Tian, iommu,
linux-kernel
On Thu, Oct 26, 2023 at 04:49:42PM +0800, Lu Baolu wrote:
> The iommu_create_device_direct_mappings() only needs to flush the caches
> when the mappings are changed in the affected domain. This is not true
> for non-DMA domains, or for devices attached to the domain that have no
> reserved regions. To avoid unnecessary cache invalidations, add a check
> before iommu_flush_iotlb_all().
>
> Fixes: a48ce36e2786 ("iommu: Prevent RESV_DIRECT devices from blocking domains")
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> ---
> drivers/iommu/iommu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
Applied, thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-10-26 8:49 [PATCH 1/1] iommu: Avoid unnecessary cache invalidations Lu Baolu
2023-10-27 4:30 ` Henry Willard
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