* [PATCH] iommu/vt-d: Fix intel_pasid_max_id
@ 2019-04-30 7:29 Eric Auger
2019-04-30 18:01 ` Jacob Pan
0 siblings, 1 reply; 3+ messages in thread
From: Eric Auger @ 2019-04-30 7:29 UTC (permalink / raw)
To: eric.auger.pro, eric.auger, joro, iommu, linux-kernel; +Cc: dwmw2
Extended Capability Register PSS field (PASID Size Supported)
corresponds to the PASID bit size -1.
"A value of N in this field indicates hardware supports PASID
field of N+1 bits (For example, value of 7 in this field,
indicates 8-bit PASIDs are supported)".
Fix the computation of intel_pasid_max_id accordingly.
Fixes: 562831747f62 ("iommu/vt-d: Global PASID name space")
Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
drivers/iommu/intel-iommu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 28cb713d728c..c3f1bfc81d2e 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3331,7 +3331,7 @@ static int __init init_dmars(void)
* than the smallest supported.
*/
if (pasid_supported(iommu)) {
- u32 temp = 2 << ecap_pss(iommu->ecap);
+ u32 temp = 2 << (ecap_pss(iommu->ecap) + 1);
intel_pasid_max_id = min_t(u32, temp,
intel_pasid_max_id);
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] iommu/vt-d: Fix intel_pasid_max_id
2019-04-30 7:29 [PATCH] iommu/vt-d: Fix intel_pasid_max_id Eric Auger
@ 2019-04-30 18:01 ` Jacob Pan
2019-04-30 20:37 ` Auger Eric
0 siblings, 1 reply; 3+ messages in thread
From: Jacob Pan @ 2019-04-30 18:01 UTC (permalink / raw)
To: Eric Auger
Cc: eric.auger.pro, joro, iommu, linux-kernel, dwmw2, jacob.jun.pan
On Tue, 30 Apr 2019 09:29:40 +0200
Eric Auger <eric.auger@redhat.com> wrote:
> Extended Capability Register PSS field (PASID Size Supported)
> corresponds to the PASID bit size -1.
>
> "A value of N in this field indicates hardware supports PASID
> field of N+1 bits (For example, value of 7 in this field,
> indicates 8-bit PASIDs are supported)".
>
> Fix the computation of intel_pasid_max_id accordingly.
>
> Fixes: 562831747f62 ("iommu/vt-d: Global PASID name space")
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
> drivers/iommu/intel-iommu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 28cb713d728c..c3f1bfc81d2e 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -3331,7 +3331,7 @@ static int __init init_dmars(void)
> * than the smallest supported.
> */
> if (pasid_supported(iommu)) {
> - u32 temp = 2 << ecap_pss(iommu->ecap);
> + u32 temp = 2 << (ecap_pss(iommu->ecap) + 1);
here it is "2 << bits" not "1 << bits", so the original code is correct.
But I agree it would be more clear to the spec. if we do:
1 << (ecap_pss(iommu->ecap) + 1);
>
> intel_pasid_max_id = min_t(u32, temp,
> intel_pasid_max_id);
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] iommu/vt-d: Fix intel_pasid_max_id
2019-04-30 18:01 ` Jacob Pan
@ 2019-04-30 20:37 ` Auger Eric
0 siblings, 0 replies; 3+ messages in thread
From: Auger Eric @ 2019-04-30 20:37 UTC (permalink / raw)
To: Jacob Pan; +Cc: eric.auger.pro, joro, iommu, linux-kernel, dwmw2
Hi Jacob,
On 4/30/19 8:01 PM, Jacob Pan wrote:
> On Tue, 30 Apr 2019 09:29:40 +0200
> Eric Auger <eric.auger@redhat.com> wrote:
>
>> Extended Capability Register PSS field (PASID Size Supported)
>> corresponds to the PASID bit size -1.
>>
>> "A value of N in this field indicates hardware supports PASID
>> field of N+1 bits (For example, value of 7 in this field,
>> indicates 8-bit PASIDs are supported)".
>>
>> Fix the computation of intel_pasid_max_id accordingly.
>>
>> Fixes: 562831747f62 ("iommu/vt-d: Global PASID name space")
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>> ---
>> drivers/iommu/intel-iommu.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
>> index 28cb713d728c..c3f1bfc81d2e 100644
>> --- a/drivers/iommu/intel-iommu.c
>> +++ b/drivers/iommu/intel-iommu.c
>> @@ -3331,7 +3331,7 @@ static int __init init_dmars(void)
>> * than the smallest supported.
>> */
>> if (pasid_supported(iommu)) {
>> - u32 temp = 2 << ecap_pss(iommu->ecap);
>> + u32 temp = 2 << (ecap_pss(iommu->ecap) + 1);
> here it is "2 << bits" not "1 << bits", so the original code is correct.
>
> But I agree it would be more clear to the spec. if we do:
> 1 << (ecap_pss(iommu->ecap) + 1);
Oups OK, my eyes. Forget it :-(
Thanks
Eric
>>
>> intel_pasid_max_id = min_t(u32, temp,
>> intel_pasid_max_id);
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-04-30 7:29 [PATCH] iommu/vt-d: Fix intel_pasid_max_id Eric Auger
2019-04-30 18:01 ` Jacob Pan
2019-04-30 20:37 ` Auger Eric
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