2021-03-20 02:54:15

by Baolu Lu

Subject: [PATCH v2 1/1] iommu/vt-d: Don't set then clear private data in prq_event_thread()

The VT-d specification (section 7.6) requires that the value in the
Private Data field of a Page Group Response Descriptor must match
the value in the Private Data field of the respective Page Request
Descriptor.

The private data field of a page group response descriptor is set then
immediately cleared in prq_event_thread(). This breaks the rule defined
by the VT-d specification. Fix it by moving clearing code up.

Fixes: 5b438f4ba315d ("iommu/vt-d: Support page request in scalable mode")
Cc: Jacob Pan <[email protected]>
Reviewed-by: Liu Yi L <[email protected]>
Signed-off-by: Lu Baolu <[email protected]>
---
drivers/iommu/intel/svm.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

Log:
v1->v2:
- v1: https://lore.kernel.org/linux-iommu/[email protected]/
- Refine the commit title to make the affected field clear.
- Refine the commit message to declare why the change matters.

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 677d7f6b43bb..5d590d63ab52 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -1034,12 +1034,12 @@ static irqreturn_t prq_event_thread(int irq, void *d)
QI_PGRP_RESP_TYPE;
resp.qw1 = QI_PGRP_IDX(req->prg_index) |
QI_PGRP_LPIG(req->lpig);
+ resp.qw2 = 0;
+ resp.qw3 = 0;

if (req->priv_data_present)
memcpy(&resp.qw2, req->priv_data,
sizeof(req->priv_data));
- resp.qw2 = 0;
- resp.qw3 = 0;
qi_submit_sync(iommu, &resp, 1, 0);
}
prq_advance:
--
2.25.1

2021-04-07 20:31:05

by Joerg Roedel

Subject: Re: [PATCH v2 1/1] iommu/vt-d: Don't set then clear private data in prq_event_thread()

On Sat, Mar 20, 2021 at 10:41:56AM +0800, Lu Baolu wrote:
> drivers/iommu/intel/svm.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)

Applied, thanks.