This is a note to let you know that I've just added the patch titled
iommu/vt-d: Don't read VCCAP register unless it exists
to the 5.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iommu-vt-d-don-t-read-vccap-register-unless-it-exists.patch
and it can be found in the queue-5.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d76b42e92780c3587c1a998a3a943b501c137553 Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw@xxxxxxxxxxxx>
Date: Thu, 26 Nov 2020 11:13:51 +0000
Subject: iommu/vt-d: Don't read VCCAP register unless it exists
From: David Woodhouse <dwmw@xxxxxxxxxxxx>
commit d76b42e92780c3587c1a998a3a943b501c137553 upstream.
My virtual IOMMU implementation is whining that the guest is reading a
register that doesn't exist. Only read the VCCAP_REG if the corresponding
capability is set in ECAP_REG to indicate that it actually exists.
Fixes: 3375303e8287 ("iommu/vt-d: Add custom allocator for IOASID")
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Reviewed-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v5.7+
Acked-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/de32b150ffaa752e0cff8571b17dfb1213fbe71c.camel@xxxxxxxxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/iommu/intel/dmar.c | 3 ++-
drivers/iommu/intel/iommu.c | 4 ++--
2 files changed, 4 insertions(+), 3 deletions(-)
--- a/drivers/iommu/intel/dmar.c
+++ b/drivers/iommu/intel/dmar.c
@@ -964,7 +964,8 @@ static int map_iommu(struct intel_iommu
warn_invalid_dmar(phys_addr, " returns all ones");
goto unmap;
}
- iommu->vccap = dmar_readq(iommu->reg + DMAR_VCCAP_REG);
+ if (ecap_vcs(iommu->ecap))
+ iommu->vccap = dmar_readq(iommu->reg + DMAR_VCCAP_REG);
/* the registers might be more than one page */
map_size = max_t(int, ecap_max_iotlb_offset(iommu->ecap),
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1798,7 +1798,7 @@ static void free_dmar_iommu(struct intel
if (ecap_prs(iommu->ecap))
intel_svm_finish_prq(iommu);
}
- if (ecap_vcs(iommu->ecap) && vccap_pasid(iommu->vccap))
+ if (vccap_pasid(iommu->vccap))
ioasid_unregister_allocator(&iommu->pasid_allocator);
#endif
@@ -3177,7 +3177,7 @@ static void register_pasid_allocator(str
* is active. All vIOMMU allocators will eventually be calling the same
* host allocator.
*/
- if (!ecap_vcs(iommu->ecap) || !vccap_pasid(iommu->vccap))
+ if (!vccap_pasid(iommu->vccap))
return;
pr_info("Register custom PASID allocator\n");
Patches currently in stable-queue which might be from dwmw@xxxxxxxxxxxx are
queue-5.9/kvm-x86-fix-split-irqchip-vs-interrupt-injection-window-request.patch
queue-5.9/kvm-x86-handle-lapic_in_kernel-case-in-kvm_cpu_-_extint.patch
queue-5.9/iommu-vt-d-don-t-read-vccap-register-unless-it-exists.patch
