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* [PATCH] iommu/amd: Set translation valid bit only when IO page tables are in used
@ 2022-04-20 11:29 ` Suravee Suthikulpanit via iommu
  0 siblings, 0 replies; 6+ messages in thread
From: Suravee Suthikulpanit @ 2022-04-20 11:29 UTC (permalink / raw)
  To: linux-kernel, iommu; +Cc: joro, vasant.hegde, jon.grimm, Suravee Suthikulpanit

On AMD system with SNP enabled, IOMMU hardware checks the host translation
valid (TV) and guest translation valid (GV) bits in the device
table entry (DTE) before accessing the corresponded page tables.

However, current IOMMU driver sets the TV bit for all devices
regardless of whether the host page table is in used.
This results in ILLEGAL_DEV_TABLE_ENTRY event for devices, which
do not the host page table root pointer set up.

Thefore, only set TV bit when host or guest page tables are in used.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/init.c  |  4 +---
 drivers/iommu/amd/iommu.c | 13 +++++++++++--
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index b4a798c7b347..4f483f22e58c 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -2337,10 +2337,8 @@ static void init_device_table_dma(void)
 {
 	u32 devid;
 
-	for (devid = 0; devid <= amd_iommu_last_bdf; ++devid) {
+	for (devid = 0; devid <= amd_iommu_last_bdf; ++devid)
 		set_dev_entry_bit(devid, DEV_ENTRY_VALID);
-		set_dev_entry_bit(devid, DEV_ENTRY_TRANSLATION);
-	}
 }
 
 static void __init uninit_device_table_dma(void)
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index a1ada7bff44e..6dd35998e53c 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1473,7 +1473,7 @@ static void set_dte_entry(u16 devid, struct protection_domain *domain,
 
 	pte_root |= (domain->iop.mode & DEV_ENTRY_MODE_MASK)
 		    << DEV_ENTRY_MODE_SHIFT;
-	pte_root |= DTE_FLAG_IR | DTE_FLAG_IW | DTE_FLAG_V | DTE_FLAG_TV;
+	pte_root |= DTE_FLAG_IR | DTE_FLAG_IW | DTE_FLAG_V;
 
 	flags = amd_iommu_dev_table[devid].data[1];
 
@@ -1513,6 +1513,15 @@ static void set_dte_entry(u16 devid, struct protection_domain *domain,
 		flags    |= tmp;
 	}
 
+	/*
+	 * Only set TV bit when:
+	 *   - IOMMUv1 table is in used.
+	 *   - IOMMUv2 table is in used.
+	 */
+	if ((domain->iop.mode != PAGE_MODE_NONE) ||
+	    (domain->flags & PD_IOMMUV2_MASK))
+		pte_root |= DTE_FLAG_TV;
+
 	flags &= ~DEV_DOMID_MASK;
 	flags |= domain->id;
 
@@ -1535,7 +1544,7 @@ static void set_dte_entry(u16 devid, struct protection_domain *domain,
 static void clear_dte_entry(u16 devid)
 {
 	/* remove entry from the device table seen by the hardware */
-	amd_iommu_dev_table[devid].data[0]  = DTE_FLAG_V | DTE_FLAG_TV;
+	amd_iommu_dev_table[devid].data[0]  = DTE_FLAG_V;
 	amd_iommu_dev_table[devid].data[1] &= DTE_FLAG_MASK;
 
 	amd_iommu_apply_erratum_63(devid);
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [PATCH] iommu/amd: Set translation valid bit only when IO page tables are in used
@ 2022-04-20 11:29 ` Suravee Suthikulpanit via iommu
  0 siblings, 0 replies; 6+ messages in thread
From: Suravee Suthikulpanit via iommu @ 2022-04-20 11:29 UTC (permalink / raw)
  To: linux-kernel, iommu; +Cc: jon.grimm, vasant.hegde

On AMD system with SNP enabled, IOMMU hardware checks the host translation
valid (TV) and guest translation valid (GV) bits in the device
table entry (DTE) before accessing the corresponded page tables.

However, current IOMMU driver sets the TV bit for all devices
regardless of whether the host page table is in used.
This results in ILLEGAL_DEV_TABLE_ENTRY event for devices, which
do not the host page table root pointer set up.

Thefore, only set TV bit when host or guest page tables are in used.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/init.c  |  4 +---
 drivers/iommu/amd/iommu.c | 13 +++++++++++--
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index b4a798c7b347..4f483f22e58c 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -2337,10 +2337,8 @@ static void init_device_table_dma(void)
 {
 	u32 devid;
 
-	for (devid = 0; devid <= amd_iommu_last_bdf; ++devid) {
+	for (devid = 0; devid <= amd_iommu_last_bdf; ++devid)
 		set_dev_entry_bit(devid, DEV_ENTRY_VALID);
-		set_dev_entry_bit(devid, DEV_ENTRY_TRANSLATION);
-	}
 }
 
 static void __init uninit_device_table_dma(void)
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index a1ada7bff44e..6dd35998e53c 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1473,7 +1473,7 @@ static void set_dte_entry(u16 devid, struct protection_domain *domain,
 
 	pte_root |= (domain->iop.mode & DEV_ENTRY_MODE_MASK)
 		    << DEV_ENTRY_MODE_SHIFT;
-	pte_root |= DTE_FLAG_IR | DTE_FLAG_IW | DTE_FLAG_V | DTE_FLAG_TV;
+	pte_root |= DTE_FLAG_IR | DTE_FLAG_IW | DTE_FLAG_V;
 
 	flags = amd_iommu_dev_table[devid].data[1];
 
@@ -1513,6 +1513,15 @@ static void set_dte_entry(u16 devid, struct protection_domain *domain,
 		flags    |= tmp;
 	}
 
+	/*
+	 * Only set TV bit when:
+	 *   - IOMMUv1 table is in used.
+	 *   - IOMMUv2 table is in used.
+	 */
+	if ((domain->iop.mode != PAGE_MODE_NONE) ||
+	    (domain->flags & PD_IOMMUV2_MASK))
+		pte_root |= DTE_FLAG_TV;
+
 	flags &= ~DEV_DOMID_MASK;
 	flags |= domain->id;
 
@@ -1535,7 +1544,7 @@ static void set_dte_entry(u16 devid, struct protection_domain *domain,
 static void clear_dte_entry(u16 devid)
 {
 	/* remove entry from the device table seen by the hardware */
-	amd_iommu_dev_table[devid].data[0]  = DTE_FLAG_V | DTE_FLAG_TV;
+	amd_iommu_dev_table[devid].data[0]  = DTE_FLAG_V;
 	amd_iommu_dev_table[devid].data[1] &= DTE_FLAG_MASK;
 
 	amd_iommu_apply_erratum_63(devid);
-- 
2.25.1

_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH] iommu/amd: Set translation valid bit only when IO page tables are in used
  2022-04-20 11:29 ` Suravee Suthikulpanit via iommu
@ 2022-04-28  7:34   ` Vasant Hegde via iommu
  -1 siblings, 0 replies; 6+ messages in thread
From: Vasant Hegde @ 2022-04-28  7:34 UTC (permalink / raw)
  To: Suravee Suthikulpanit, linux-kernel, iommu; +Cc: jon.grimm

On 4/20/2022 4:59 PM, Suravee Suthikulpanit via iommu wrote:
> On AMD system with SNP enabled, IOMMU hardware checks the host translation
> valid (TV) and guest translation valid (GV) bits in the device
> table entry (DTE) before accessing the corresponded page tables.
> 
> However, current IOMMU driver sets the TV bit for all devices
> regardless of whether the host page table is in used.
> This results in ILLEGAL_DEV_TABLE_ENTRY event for devices, which
> do not the host page table root pointer set up.
> 
> Thefore, only set TV bit when host or guest page tables are in used.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

Looks good to me.

Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>

-Vasant


^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] iommu/amd: Set translation valid bit only when IO page tables are in used
@ 2022-04-28  7:34   ` Vasant Hegde via iommu
  0 siblings, 0 replies; 6+ messages in thread
From: Vasant Hegde via iommu @ 2022-04-28  7:34 UTC (permalink / raw)
  To: Suravee Suthikulpanit, linux-kernel, iommu; +Cc: jon.grimm

On 4/20/2022 4:59 PM, Suravee Suthikulpanit via iommu wrote:
> On AMD system with SNP enabled, IOMMU hardware checks the host translation
> valid (TV) and guest translation valid (GV) bits in the device
> table entry (DTE) before accessing the corresponded page tables.
> 
> However, current IOMMU driver sets the TV bit for all devices
> regardless of whether the host page table is in used.
> This results in ILLEGAL_DEV_TABLE_ENTRY event for devices, which
> do not the host page table root pointer set up.
> 
> Thefore, only set TV bit when host or guest page tables are in used.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

Looks good to me.

Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>

-Vasant

_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] iommu/amd: Set translation valid bit only when IO page tables are in used
  2022-04-20 11:29 ` Suravee Suthikulpanit via iommu
@ 2022-04-28 17:16   ` Suravee Suthikulpanit via iommu
  -1 siblings, 0 replies; 6+ messages in thread
From: Suravee Suthikulpanit @ 2022-04-28 17:16 UTC (permalink / raw)
  To: linux-kernel, iommu; +Cc: joro, vasant.hegde, jon.grimm



On 4/20/22 6:29 PM, Suravee Suthikulpanit wrote:
> On AMD system with SNP enabled, IOMMU hardware checks the host translation
> valid (TV) and guest translation valid (GV) bits in the device
> table entry (DTE) before accessing the corresponded page tables.
> 
> However, current IOMMU driver sets the TV bit for all devices
> regardless of whether the host page table is in used.
> This results in ILLEGAL_DEV_TABLE_ENTRY event for devices, which
> do not the host page table root pointer set up.
> 
> Thefore, only set TV bit when host or guest page tables are in used.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
>

I found a bug in this patch. I will send out v2 with the fix.

Regards,
Suravee

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] iommu/amd: Set translation valid bit only when IO page tables are in used
@ 2022-04-28 17:16   ` Suravee Suthikulpanit via iommu
  0 siblings, 0 replies; 6+ messages in thread
From: Suravee Suthikulpanit via iommu @ 2022-04-28 17:16 UTC (permalink / raw)
  To: linux-kernel, iommu; +Cc: jon.grimm, vasant.hegde



On 4/20/22 6:29 PM, Suravee Suthikulpanit wrote:
> On AMD system with SNP enabled, IOMMU hardware checks the host translation
> valid (TV) and guest translation valid (GV) bits in the device
> table entry (DTE) before accessing the corresponded page tables.
> 
> However, current IOMMU driver sets the TV bit for all devices
> regardless of whether the host page table is in used.
> This results in ILLEGAL_DEV_TABLE_ENTRY event for devices, which
> do not the host page table root pointer set up.
> 
> Thefore, only set TV bit when host or guest page tables are in used.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
>

I found a bug in this patch. I will send out v2 with the fix.

Regards,
Suravee
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-04-28 17:16 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-04-20 11:29 [PATCH] iommu/amd: Set translation valid bit only when IO page tables are in used Suravee Suthikulpanit
2022-04-20 11:29 ` Suravee Suthikulpanit via iommu
2022-04-28  7:34 ` Vasant Hegde
2022-04-28  7:34   ` Vasant Hegde via iommu
2022-04-28 17:16 ` Suravee Suthikulpanit
2022-04-28 17:16   ` Suravee Suthikulpanit via iommu

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