[PATCH v2] iommu/intel-iommu: fix pasid table size encoding

[PATCH v2] iommu/intel-iommu: fix pasid table size encoding

[Jacob Pan]

Different encodings are used to represent supported PASID bits
and number of PASID table entries.
The current code assigns ecap_pss directly to extended context
table entry PTS which is wrong and could result in writing
non-zero bits to the reserved fields. IOMMU fault reason
11 will be reported when reserved bits are nonzero.
This patch converts ecap_pss to extend context entry pts encoding
based on VT-d spec. Chapter 9.4 as follows:
 - number of PASID bits = ecap_pss + 1
 - number of PASID table entries = 2^(pts + 5)
Software assigned limit of pasid_max value is also respected to
match the allocation limitation of PASID table.

cc: Mika Kuoppala <mika.kuoppala-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
cc: Ashok Raj <ashok.raj-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Jacob Pan <jacob.jun.pan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 drivers/iommu/intel-iommu.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 27596e6..5d9cddc 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -5173,6 +5173,25 @@ static void intel_iommu_remove_device(struct device *dev)
 }
 
 #ifdef CONFIG_INTEL_IOMMU_SVM
+#define MAX_NR_PASID_BITS (20)
+static inline unsigned long intel_iommu_get_pts(struct intel_iommu *iommu)
+{
+	/*
+	 * Convert ecap_pss to extend context entry pts encoding, also
+	 * respect the soft pasid_max value set by the iommu.
+	 * - number of PASID bits = ecap_pss + 1
+	 * - number of PASID table entries = 2^(pts + 5)
+	 * Therefore, pts = ecap_pss - 4
+	 * e.g. KBL ecap_pss = 0x13, PASID has 20 bits, pts = 15
+	 */
+	if (ecap_pss(iommu->ecap) < 5)
+		return 0;
+
+	/* pasid_max is encoded as actual number of entries not the bits */
+	return find_first_bit((unsigned long *)&iommu->pasid_max,
+			MAX_NR_PASID_BITS) - 5;
+}
+
 int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct intel_svm_dev *sdev)
 {
 	struct device_domain_info *info;
@@ -5205,7 +5224,9 @@ int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct intel_svm_dev *sd
 
 	if (!(ctx_lo & CONTEXT_PASIDE)) {
 		context[1].hi = (u64)virt_to_phys(iommu->pasid_state_table);
-		context[1].lo = (u64)virt_to_phys(iommu->pasid_table) | ecap_pss(iommu->ecap);
+		context[1].lo = (u64)virt_to_phys(iommu->pasid_table) |
+			intel_iommu_get_pts(iommu);
+
 		wmb();
 		/* CONTEXT_TT_MULTI_LEVEL and CONTEXT_TT_DEV_IOTLB are both
 		 * extended to permit requests-with-PASID if the PASIDE bit
-- 
2.7.4

Re: [PATCH v2] iommu/intel-iommu: fix pasid table size encoding

[Jacob Pan]

Hi Joerg/David,

Just wondering if you have any more comments?

Thanks,

Jacob

On Tue,  6 Dec 2016 10:14:23 -0800
Jacob Pan <jacob.jun.pan@linux.intel.com> wrote:

> Different encodings are used to represent supported PASID bits
> and number of PASID table entries.
> The current code assigns ecap_pss directly to extended context
> table entry PTS which is wrong and could result in writing
> non-zero bits to the reserved fields. IOMMU fault reason
> 11 will be reported when reserved bits are nonzero.
> This patch converts ecap_pss to extend context entry pts encoding
> based on VT-d spec. Chapter 9.4 as follows:
>  - number of PASID bits = ecap_pss + 1
>  - number of PASID table entries = 2^(pts + 5)
> Software assigned limit of pasid_max value is also respected to
> match the allocation limitation of PASID table.
> 
> cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> cc: Ashok Raj <ashok.raj@intel.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
>  drivers/iommu/intel-iommu.c | 23 ++++++++++++++++++++++-
>  1 file changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 27596e6..5d9cddc 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -5173,6 +5173,25 @@ static void intel_iommu_remove_device(struct
> device *dev) }
>  
>  #ifdef CONFIG_INTEL_IOMMU_SVM
> +#define MAX_NR_PASID_BITS (20)
> +static inline unsigned long intel_iommu_get_pts(struct intel_iommu
> *iommu) +{
> +	/*
> +	 * Convert ecap_pss to extend context entry pts encoding,
> also
> +	 * respect the soft pasid_max value set by the iommu.
> +	 * - number of PASID bits = ecap_pss + 1
> +	 * - number of PASID table entries = 2^(pts + 5)
> +	 * Therefore, pts = ecap_pss - 4
> +	 * e.g. KBL ecap_pss = 0x13, PASID has 20 bits, pts = 15
> +	 */
> +	if (ecap_pss(iommu->ecap) < 5)
> +		return 0;
> +
> +	/* pasid_max is encoded as actual number of entries not the
> bits */
> +	return find_first_bit((unsigned long *)&iommu->pasid_max,
> +			MAX_NR_PASID_BITS) - 5;
> +}
> +
>  int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct
> intel_svm_dev *sdev) {
>  	struct device_domain_info *info;
> @@ -5205,7 +5224,9 @@ int intel_iommu_enable_pasid(struct intel_iommu
> *iommu, struct intel_svm_dev *sd 
>  	if (!(ctx_lo & CONTEXT_PASIDE)) {
>  		context[1].hi =
> (u64)virt_to_phys(iommu->pasid_state_table);
> -		context[1].lo =
> (u64)virt_to_phys(iommu->pasid_table) | ecap_pss(iommu->ecap);
> +		context[1].lo =
> (u64)virt_to_phys(iommu->pasid_table) |
> +			intel_iommu_get_pts(iommu);
> +
>  		wmb();
>  		/* CONTEXT_TT_MULTI_LEVEL and CONTEXT_TT_DEV_IOTLB
> are both
>  		 * extended to permit requests-with-PASID if the
> PASIDE bit

[Jacob Pan]

Re: [PATCH v2] iommu/intel-iommu: fix pasid table size encoding

[Mika Kuoppala]

Jacob Pan <jacob.jun.pan@linux.intel.com> writes:

> Different encodings are used to represent supported PASID bits
> and number of PASID table entries.
> The current code assigns ecap_pss directly to extended context
> table entry PTS which is wrong and could result in writing
> non-zero bits to the reserved fields. IOMMU fault reason
> 11 will be reported when reserved bits are nonzero.
> This patch converts ecap_pss to extend context entry pts encoding
> based on VT-d spec. Chapter 9.4 as follows:
>  - number of PASID bits = ecap_pss + 1
>  - number of PASID table entries = 2^(pts + 5)
> Software assigned limit of pasid_max value is also respected to
> match the allocation limitation of PASID table.
>
> cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> cc: Ashok Raj <ashok.raj@intel.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>

Tested-by: Mika Kuoppala <mika.kuoppala@intel.com>

> ---
>  drivers/iommu/intel-iommu.c | 23 ++++++++++++++++++++++-
>  1 file changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 27596e6..5d9cddc 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -5173,6 +5173,25 @@ static void intel_iommu_remove_device(struct device *dev)
>  }
>  
>  #ifdef CONFIG_INTEL_IOMMU_SVM
> +#define MAX_NR_PASID_BITS (20)
> +static inline unsigned long intel_iommu_get_pts(struct intel_iommu *iommu)
> +{
> +	/*
> +	 * Convert ecap_pss to extend context entry pts encoding, also
> +	 * respect the soft pasid_max value set by the iommu.
> +	 * - number of PASID bits = ecap_pss + 1
> +	 * - number of PASID table entries = 2^(pts + 5)
> +	 * Therefore, pts = ecap_pss - 4
> +	 * e.g. KBL ecap_pss = 0x13, PASID has 20 bits, pts = 15
> +	 */
> +	if (ecap_pss(iommu->ecap) < 5)
> +		return 0;
> +
> +	/* pasid_max is encoded as actual number of entries not the bits */
> +	return find_first_bit((unsigned long *)&iommu->pasid_max,
> +			MAX_NR_PASID_BITS) - 5;
> +}
> +
>  int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct intel_svm_dev *sdev)
>  {
>  	struct device_domain_info *info;
> @@ -5205,7 +5224,9 @@ int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct intel_svm_dev *sd
>  
>  	if (!(ctx_lo & CONTEXT_PASIDE)) {
>  		context[1].hi = (u64)virt_to_phys(iommu->pasid_state_table);
> -		context[1].lo = (u64)virt_to_phys(iommu->pasid_table) | ecap_pss(iommu->ecap);
> +		context[1].lo = (u64)virt_to_phys(iommu->pasid_table) |
> +			intel_iommu_get_pts(iommu);
> +
>  		wmb();
>  		/* CONTEXT_TT_MULTI_LEVEL and CONTEXT_TT_DEV_IOTLB are both
>  		 * extended to permit requests-with-PASID if the PASIDE bit
> -- 
> 2.7.4

Re: [PATCH v2] iommu/intel-iommu: fix pasid table size encoding

[Raj, Ashok]

Hi David/Joerg

Haven't heard about it from David yet, but can we queue this for 4.10? 
If you have any questions/concerns please let us know. 

Cheers,
Ashok



On Wed, Dec 14, 2016 at 02:36:40PM +0200, Mika Kuoppala wrote:
> >
> > cc: Mika Kuoppala <mika.kuoppala-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> > cc: Ashok Raj <ashok.raj-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> > Signed-off-by: Jacob Pan <jacob.jun.pan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> 
> Tested-by: Mika Kuoppala <mika.kuoppala-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

Signed-of-by: Ashok Raj <ashok.raj-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

> 
> > ---
> >  drivers/iommu/intel-iommu.c | 23 ++++++++++++++++++++++-
> >  1 file changed, 22 insertions(+), 1 deletion(-)
> >

Re: [PATCH v2] iommu/intel-iommu: fix pasid table size encoding

[Joerg Roedel]

On Thu, Dec 15, 2016 at 12:07:10PM -0800, Raj, Ashok wrote:
> Haven't heard about it from David yet, but can we queue this for 4.10? 
> If you have any questions/concerns please let us know.

I'll queue the fix when rc1 is out.



	Joerg

Re: [PATCH v2] iommu/intel-iommu: fix pasid table size encoding

[Joerg Roedel]

On Tue, Dec 06, 2016 at 10:14:23AM -0800, Jacob Pan wrote:
>  drivers/iommu/intel-iommu.c | 23 ++++++++++++++++++++++-
>  1 file changed, 22 insertions(+), 1 deletion(-)

Applied to the fixes branch, thanks.