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SubjectRe: [PATCH V2] iommu/amd: Fix logic to determine and checking max PASID
Joerg,

Do you have any concerns about the V2 of this patch?

Thanks,

Suravee

On 3/5/2014 6:54 PM, suravee.suthikulpanit@amd.com wrote:
> From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
>
> In reality, the spec can only support 16-bit PASID since
> INVALIDATE_IOTLB_PAGES and COMPLETE_PPR_REQUEST commands only allow 16-bit
> PASID. So, we updated the PASID_MASK accordingly and invoke BUG_ON
> if the hardware is reporting PASmax more than 16-bit.
>
> Besides, max PASID is defined as ((2^(PASmax+1)) - 1). The current does not
> determine this correctly.
>
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> Tested-by: Jay Cornwall <Jay.Cornwall@amd.com>
> ---
> drivers/iommu/amd_iommu.c | 4 ++--
> drivers/iommu/amd_iommu_init.c | 16 +++++++++-------
> drivers/iommu/amd_iommu_types.h | 11 ++++++++---
> 3 files changed, 19 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
> index faf0da4..66ef2cb 100644
> --- a/drivers/iommu/amd_iommu.c
> +++ b/drivers/iommu/amd_iommu.c
> @@ -963,7 +963,7 @@ static void build_inv_iommu_pasid(struct iommu_cmd *cmd, u16 domid, int pasid,
>
> address &= ~(0xfffULL);
>
> - cmd->data[0] = pasid & PASID_MASK;
> + cmd->data[0] = pasid;
> cmd->data[1] = domid;
> cmd->data[2] = lower_32_bits(address);
> cmd->data[3] = upper_32_bits(address);
> @@ -1001,7 +1001,7 @@ static void build_complete_ppr(struct iommu_cmd *cmd, u16 devid, int pasid,
>
> cmd->data[0] = devid;
> if (gn) {
> - cmd->data[1] = pasid & PASID_MASK;
> + cmd->data[1] = pasid;
> cmd->data[2] = CMD_INV_IOMMU_PAGES_GN_MASK;
> }
> cmd->data[3] = tag & 0x1ff;
> diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
> index 28b4bea..b76c58d 100644
> --- a/drivers/iommu/amd_iommu_init.c
> +++ b/drivers/iommu/amd_iommu_init.c
> @@ -150,7 +150,7 @@ int amd_iommus_present;
> bool amd_iommu_np_cache __read_mostly;
> bool amd_iommu_iotlb_sup __read_mostly = true;
>
> -u32 amd_iommu_max_pasids __read_mostly = ~0;
> +u32 amd_iommu_max_pasid __read_mostly = ~0;
>
> bool amd_iommu_v2_present __read_mostly;
> bool amd_iommu_pc_present __read_mostly;
> @@ -1231,14 +1231,16 @@ static int iommu_init_pci(struct amd_iommu *iommu)
>
> if (iommu_feature(iommu, FEATURE_GT)) {
> int glxval;
> - u32 pasids;
> - u64 shift;
> + u32 max_pasid;
> + u64 pasmax;
>
> - shift = iommu->features & FEATURE_PASID_MASK;
> - shift >>= FEATURE_PASID_SHIFT;
> - pasids = (1 << shift);
> + pasmax = iommu->features & FEATURE_PASID_MASK;
> + pasmax >>= FEATURE_PASID_SHIFT;
> + max_pasid = (1 << (pasmax + 1)) - 1;
>
> - amd_iommu_max_pasids = min(amd_iommu_max_pasids, pasids);
> + amd_iommu_max_pasid = min(amd_iommu_max_pasid, max_pasid);
> +
> + BUG_ON(amd_iommu_max_pasid & ~PASID_MASK);
>
> glxval = iommu->features & FEATURE_GLXVAL_MASK;
> glxval >>= FEATURE_GLXVAL_SHIFT;
> diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
> index e400fbe..55ba46b 100644
> --- a/drivers/iommu/amd_iommu_types.h
> +++ b/drivers/iommu/amd_iommu_types.h
> @@ -98,7 +98,12 @@
> #define FEATURE_GLXVAL_SHIFT 14
> #define FEATURE_GLXVAL_MASK (0x03ULL << FEATURE_GLXVAL_SHIFT)
>
> -#define PASID_MASK 0x000fffff
> +/* Note:
> + * The current driver only support 16-bit PASID.
> + * Currently, hardware only implement upto 16-bit PASID
> + * even though the spec says it could have upto 20 bits.
> + */
> +#define PASID_MASK 0x0000ffff
>
> /* MMIO status bits */
> #define MMIO_STATUS_EVT_INT_MASK (1 << 1)
> @@ -696,8 +701,8 @@ extern unsigned long *amd_iommu_pd_alloc_bitmap;
> */
> extern u32 amd_iommu_unmap_flush;
>
> -/* Smallest number of PASIDs supported by any IOMMU in the system */
> -extern u32 amd_iommu_max_pasids;
> +/* Smallest max PASID supported by any IOMMU in the system */
> +extern u32 amd_iommu_max_pasid;
>
> extern bool amd_iommu_v2_present;
>
>




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