Commit-ID: abf73b352b56cd6747fc64dc10612de50a5ef70c
Gitweb: http://git.kernel.org/tip/abf73b352b56cd6747fc64dc10612de50a5ef70c
Author: Joerg Roedel <jroedel@xxxxxxx>
AuthorDate: Wed, 14 Sep 2016 11:41:59 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 14 Sep 2016 17:26:18 +0200
iommu/amd: Don't put completion-wait semaphore on stack
The semaphore used by the AMD IOMMU to signal command
completion lived on the stack until now, which was safe as
the driver busy-waited on the semaphore with IRQs disabled,
so the stack can't go away under the driver.
But the recently introduced vmap-based stacks break this as
the physical address of the semaphore can't be determinded
easily anymore. The driver used the __pa() macro, but that
only works in the direct-mapping. The result were
Completion-Wait timeout errors seen by the IOMMU driver,
breaking system boot.
Since putting the semaphore on the stack is bad design
anyway, move the semaphore into 'struct amd_iommu'. It is
protected by the per-iommu lock and now in the direct
mapping again. This fixes the Completion-Wait timeout errors
and makes AMD IOMMU systems boot again with vmap-based
stacks enabled.
Reported-by: Borislav Petkov <bp@xxxxxxxxx>
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
drivers/iommu/amd_iommu.c | 14 ++++++++------
drivers/iommu/amd_iommu_types.h | 2 ++
2 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 96de97a..1307e73 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -957,15 +957,16 @@ again:
if (left <= 2) {
struct iommu_cmd sync_cmd;
- volatile u64 sem = 0;
int ret;
- build_completion_wait(&sync_cmd, (u64)&sem);
+ iommu->cmd_sem = 0;
+
+ build_completion_wait(&sync_cmd, (u64)&iommu->cmd_sem);
copy_cmd_to_buffer(iommu, &sync_cmd, tail);
spin_unlock_irqrestore(&iommu->lock, flags);
- if ((ret = wait_on_sem(&sem)) != 0)
+ if ((ret = wait_on_sem(&iommu->cmd_sem)) != 0)
return ret;
goto again;
@@ -993,19 +994,20 @@ static int iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
static int iommu_completion_wait(struct amd_iommu *iommu)
{
struct iommu_cmd cmd;
- volatile u64 sem = 0;
int ret;
if (!iommu->need_sync)
return 0;
- build_completion_wait(&cmd, (u64)&sem);
+ iommu->cmd_sem = 0;
+
+ build_completion_wait(&cmd, (u64)&iommu->cmd_sem);
ret = iommu_queue_command_sync(iommu, &cmd, false);
if (ret)
return ret;
- return wait_on_sem(&sem);
+ return wait_on_sem(&iommu->cmd_sem);
}
static int iommu_flush_dte(struct amd_iommu *iommu, u16 devid)
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index caf5e38..9652848 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -524,6 +524,8 @@ struct amd_iommu {
struct irq_domain *ir_domain;
struct irq_domain *msi_domain;
#endif
+
+ volatile u64 __aligned(8) cmd_sem;
};
#define ACPIHID_UID_LEN 256
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