RE: [PATCH v2 1/2] iommu/amd: Enable swiotlb in all cases
[AMD Official Use Only] > On Wed, Apr 06, 2022 at 05:04:52PM +, Limonciello, Mario wrote: > > Considering before this fix effectively swiotlb was turned off on most AMD > > systems, when this is picked up I think y'all should consider to add a: > > > > Cc: sta...@vger.kernel.org # 5.11+ > > Agreed. I think this is for Joerg to pick up, and I'd love to see it > picked up soon as I'll have to rebase my > > "cleanup swiotlb initialization" series on top of it. Joerg, Just want to double check this wasn't lost the last few weeks. I was just checking iommu.git/next and didn't notice it still. Thanks, ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH v2 1/2] iommu/amd: Enable swiotlb in all cases
On Thu, Apr 07, 2022 at 02:31:44PM +0100, Robin Murphy wrote: > FWIW it's also broken for another niche case where > iommu_default_passthrough() == false at init, but the user later changes a > 32-bit device's default domain type to passthrough via sysfs, such that it > starts needing regular dma-direct bouncing. Yeah. We also have yet another issue: swiotlb is not allocate if there is no memory outside the 4GB physical address space. I think I can fix that easily after my swiotlb init series goes in, before that it would be a bit of a mess spread over all the architectures. ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH v2 1/2] iommu/amd: Enable swiotlb in all cases
On 2022-04-04 21:47, Mario Limonciello wrote:
Previously the AMD IOMMU would only enable SWIOTLB in certain
circumstances:
* IOMMU in passthrough mode
* SME enabled
This logic however doesn't work when an untrusted device is plugged in
that doesn't do page aligned DMA transactions. The expectation is
that a bounce buffer is used for those transactions.
This fails like this:
swiotlb buffer is full (sz: 4096 bytes), total 0 (slots), used 0 (slots)
That happens because the bounce buffers have been allocated, followed by
freed during startup but the bounce buffering code expects that all IOMMUs
have left it enabled.
Remove the criteria to set up bounce buffers on AMD systems to ensure
they're always available for supporting untrusted devices.
FWIW it's also broken for another niche case where
iommu_default_passthrough() == false at init, but the user later changes
a 32-bit device's default domain type to passthrough via sysfs, such
that it starts needing regular dma-direct bouncing.
Reviewed-by: Robin Murphy
Fixes: 82612d66d51d ("iommu: Allow the dma-iommu api to use bounce buffers")
Suggested-by: Christoph Hellwig
Signed-off-by: Mario Limonciello
---
v1->v2:
* Enable swiotlb for AMD instead of ignoring it for inactive
drivers/iommu/amd/iommu.c | 7 ---
1 file changed, 7 deletions(-)
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index a1ada7bff44e..079694f894b8 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1838,17 +1838,10 @@ void amd_iommu_domain_update(struct protection_domain
*domain)
amd_iommu_domain_flush_complete(domain);
}
-static void __init amd_iommu_init_dma_ops(void)
-{
- swiotlb = (iommu_default_passthrough() || sme_me_mask) ? 1 : 0;
-}
-
int __init amd_iommu_init_api(void)
{
int err;
- amd_iommu_init_dma_ops();
-
err = bus_set_iommu(&pci_bus_type, &amd_iommu_ops);
if (err)
return err;
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Re: [PATCH v2 1/2] iommu/amd: Enable swiotlb in all cases
On Wed, Apr 06, 2022 at 05:04:52PM +, Limonciello, Mario wrote: > Considering before this fix effectively swiotlb was turned off on most AMD > systems, when this is picked up I think y'all should consider to add a: > > Cc: sta...@vger.kernel.org # 5.11+ Agreed. I think this is for Joerg to pick up, and I'd love to see it picked up soon as I'll have to rebase my "cleanup swiotlb initialization" series on top of it. ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
RE: [PATCH v2 1/2] iommu/amd: Enable swiotlb in all cases
[Public] > -Original Message- > From: Christoph Hellwig > Sent: Monday, April 4, 2022 23:34 > To: Limonciello, Mario > Cc: Joerg Roedel ; Will Deacon ; > Christoph Hellwig ; Marek Szyprowski > ; Robin Murphy ; > open list:IOMMU DRIVERS ; > Suthikulpanit, Suravee ; Hegde, Vasant > ; open list > Subject: Re: [PATCH v2 1/2] iommu/amd: Enable swiotlb in all cases > > Looks good: > > Reviewed-by: Christoph Hellwig Thanks! Considering before this fix effectively swiotlb was turned off on most AMD systems, when this is picked up I think y'all should consider to add a: Cc: sta...@vger.kernel.org # 5.11+ As well. ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH v2 1/2] iommu/amd: Enable swiotlb in all cases
Looks good: Reviewed-by: Christoph Hellwig ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
[PATCH v2 1/2] iommu/amd: Enable swiotlb in all cases
Previously the AMD IOMMU would only enable SWIOTLB in certain
circumstances:
* IOMMU in passthrough mode
* SME enabled
This logic however doesn't work when an untrusted device is plugged in
that doesn't do page aligned DMA transactions. The expectation is
that a bounce buffer is used for those transactions.
This fails like this:
swiotlb buffer is full (sz: 4096 bytes), total 0 (slots), used 0 (slots)
That happens because the bounce buffers have been allocated, followed by
freed during startup but the bounce buffering code expects that all IOMMUs
have left it enabled.
Remove the criteria to set up bounce buffers on AMD systems to ensure
they're always available for supporting untrusted devices.
Fixes: 82612d66d51d ("iommu: Allow the dma-iommu api to use bounce buffers")
Suggested-by: Christoph Hellwig
Signed-off-by: Mario Limonciello
---
v1->v2:
* Enable swiotlb for AMD instead of ignoring it for inactive
drivers/iommu/amd/iommu.c | 7 ---
1 file changed, 7 deletions(-)
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index a1ada7bff44e..079694f894b8 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1838,17 +1838,10 @@ void amd_iommu_domain_update(struct protection_domain
*domain)
amd_iommu_domain_flush_complete(domain);
}
-static void __init amd_iommu_init_dma_ops(void)
-{
- swiotlb = (iommu_default_passthrough() || sme_me_mask) ? 1 : 0;
-}
-
int __init amd_iommu_init_api(void)
{
int err;
- amd_iommu_init_dma_ops();
-
err = bus_set_iommu(&pci_bus_type, &amd_iommu_ops);
if (err)
return err;
--
2.34.1
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