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authorJoerg Roedel <jroedel@suse.de>2016-09-14 12:41:59 +0300
committerIngo Molnar <mingo@kernel.org>2016-09-15 12:28:19 +0300
commit4bf5beef578e46393f11eb69dda7d17a065e05ff (patch)
treea67cc100152e095bd32a62abe2257d7d83c491e2 /drivers/iommu
parent15f4eae70d365bba26854c90b6002aaabb18c8aa (diff)
downloadlinux-4bf5beef578e46393f11eb69dda7d17a065e05ff.tar.xz
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@alien8.de> Signed-off-by: Joerg Roedel <jroedel@suse.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'drivers/iommu')
-rw-r--r--drivers/iommu/amd_iommu.c51
-rw-r--r--drivers/iommu/amd_iommu_types.h2
2 files changed, 37 insertions, 16 deletions
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 96de97a46079..4025291ea0ae 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -940,15 +940,13 @@ static void build_inv_irt(struct iommu_cmd *cmd, u16 devid)
* Writes the command to the IOMMUs command buffer and informs the
* hardware about the new command.
*/
-static int iommu_queue_command_sync(struct amd_iommu *iommu,
- struct iommu_cmd *cmd,
- bool sync)
+static int __iommu_queue_command_sync(struct amd_iommu *iommu,
+ struct iommu_cmd *cmd,
+ bool sync)
{
u32 left, tail, head, next_tail;
- unsigned long flags;
again:
- spin_lock_irqsave(&iommu->lock, flags);
head = readl(iommu->mmio_base + MMIO_CMD_HEAD_OFFSET);
tail = readl(iommu->mmio_base + MMIO_CMD_TAIL_OFFSET);
@@ -957,15 +955,14 @@ again:
if (left <= 2) {
struct iommu_cmd sync_cmd;
- volatile u64 sem = 0;
int ret;
- build_completion_wait(&sync_cmd, (u64)&sem);
- copy_cmd_to_buffer(iommu, &sync_cmd, tail);
+ iommu->cmd_sem = 0;
- spin_unlock_irqrestore(&iommu->lock, flags);
+ build_completion_wait(&sync_cmd, (u64)&iommu->cmd_sem);
+ copy_cmd_to_buffer(iommu, &sync_cmd, tail);
- if ((ret = wait_on_sem(&sem)) != 0)
+ if ((ret = wait_on_sem(&iommu->cmd_sem)) != 0)
return ret;
goto again;
@@ -976,9 +973,21 @@ again:
/* We need to sync now to make sure all commands are processed */
iommu->need_sync = sync;
+ return 0;
+}
+
+static int iommu_queue_command_sync(struct amd_iommu *iommu,
+ struct iommu_cmd *cmd,
+ bool sync)
+{
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&iommu->lock, flags);
+ ret = __iommu_queue_command_sync(iommu, cmd, sync);
spin_unlock_irqrestore(&iommu->lock, flags);
- return 0;
+ return ret;
}
static int iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
@@ -993,19 +1002,29 @@ 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;
+ unsigned long flags;
int ret;
if (!iommu->need_sync)
return 0;
- build_completion_wait(&cmd, (u64)&sem);
- ret = iommu_queue_command_sync(iommu, &cmd, false);
+ build_completion_wait(&cmd, (u64)&iommu->cmd_sem);
+
+ spin_lock_irqsave(&iommu->lock, flags);
+
+ iommu->cmd_sem = 0;
+
+ ret = __iommu_queue_command_sync(iommu, &cmd, false);
if (ret)
- return ret;
+ goto out_unlock;
+
+ ret = wait_on_sem(&iommu->cmd_sem);
- return wait_on_sem(&sem);
+out_unlock:
+ spin_unlock_irqrestore(&iommu->lock, flags);
+
+ return ret;
}
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 caf5e3822715..9652848e3155 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