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Message-ID: <20200702115454.058bd198@x1.home>
Date: Thu, 2 Jul 2020 11:54:54 -0600
From: Alex Williamson <alex.williamson@...hat.com>
To: Liu Yi L <yi.l.liu@...el.com>
Cc: eric.auger@...hat.com, baolu.lu@...ux.intel.com, joro@...tes.org,
kevin.tian@...el.com, jacob.jun.pan@...ux.intel.com,
ashok.raj@...el.com, jun.j.tian@...el.com, yi.y.sun@...el.com,
jean-philippe@...aro.org, peterx@...hat.com, hao.wu@...el.com,
iommu@...ts.linux-foundation.org, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 02/14] iommu: Report domain nesting info
On Wed, 24 Jun 2020 01:55:15 -0700
Liu Yi L <yi.l.liu@...el.com> wrote:
> IOMMUs that support nesting translation needs report the capability info
> to userspace, e.g. the format of first level/stage paging structures.
>
> This patch reports nesting info by DOMAIN_ATTR_NESTING. Caller can get
> nesting info after setting DOMAIN_ATTR_NESTING.
>
> v2 -> v3:
> *) remvoe cap/ecap_mask in iommu_nesting_info.
> *) reuse DOMAIN_ATTR_NESTING to get nesting info.
> *) return an empty iommu_nesting_info for SMMU drivers per Jean'
> suggestion.
>
> Cc: Kevin Tian <kevin.tian@...el.com>
> CC: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> Cc: Alex Williamson <alex.williamson@...hat.com>
> Cc: Eric Auger <eric.auger@...hat.com>
> Cc: Jean-Philippe Brucker <jean-philippe@...aro.org>
> Cc: Joerg Roedel <joro@...tes.org>
> Cc: Lu Baolu <baolu.lu@...ux.intel.com>
> Signed-off-by: Liu Yi L <yi.l.liu@...el.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> ---
> drivers/iommu/arm-smmu-v3.c | 29 ++++++++++++++++++++--
> drivers/iommu/arm-smmu.c | 29 ++++++++++++++++++++--
> include/uapi/linux/iommu.h | 59 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 113 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index f578677..0c45d4d 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -3019,6 +3019,32 @@ static struct iommu_group *arm_smmu_device_group(struct device *dev)
> return group;
> }
>
> +static int arm_smmu_domain_nesting_info(struct arm_smmu_domain *smmu_domain,
> + void *data)
> +{
> + struct iommu_nesting_info *info = (struct iommu_nesting_info *) data;
> + u32 size;
> +
> + if (!info || smmu_domain->stage != ARM_SMMU_DOMAIN_NESTED)
> + return -ENODEV;
> +
> + size = sizeof(struct iommu_nesting_info);
> +
> + /*
> + * if provided buffer size is not equal to the size, should
> + * return 0 and also the expected buffer size to caller.
> + */
> + if (info->size != size) {
> + info->size = size;
> + return 0;
> + }
> +
> + /* report an empty iommu_nesting_info for now */
> + memset(info, 0x0, size);
> + info->size = size;
> + return 0;
> +}
> +
> static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
> enum iommu_attr attr, void *data)
> {
> @@ -3028,8 +3054,7 @@ static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
> case IOMMU_DOMAIN_UNMANAGED:
> switch (attr) {
> case DOMAIN_ATTR_NESTING:
> - *(int *)data = (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED);
> - return 0;
> + return arm_smmu_domain_nesting_info(smmu_domain, data);
> default:
> return -ENODEV;
> }
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 243bc4c..908607d 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -1506,6 +1506,32 @@ static struct iommu_group *arm_smmu_device_group(struct device *dev)
> return group;
> }
>
> +static int arm_smmu_domain_nesting_info(struct arm_smmu_domain *smmu_domain,
> + void *data)
> +{
> + struct iommu_nesting_info *info = (struct iommu_nesting_info *) data;
> + u32 size;
> +
> + if (!info || smmu_domain->stage != ARM_SMMU_DOMAIN_NESTED)
> + return -ENODEV;
> +
> + size = sizeof(struct iommu_nesting_info);
> +
> + /*
> + * if provided buffer size is not equal to the size, should
> + * return 0 and also the expected buffer size to caller.
> + */
> + if (info->size != size) {
> + info->size = size;
> + return 0;
> + }
> +
> + /* report an empty iommu_nesting_info for now */
> + memset(info, 0x0, size);
> + info->size = size;
> + return 0;
> +}
> +
> static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
> enum iommu_attr attr, void *data)
> {
> @@ -1515,8 +1541,7 @@ static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
> case IOMMU_DOMAIN_UNMANAGED:
> switch (attr) {
> case DOMAIN_ATTR_NESTING:
> - *(int *)data = (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED);
> - return 0;
> + return arm_smmu_domain_nesting_info(smmu_domain, data);
> default:
> return -ENODEV;
> }
> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> index 1afc661..898c99a 100644
> --- a/include/uapi/linux/iommu.h
> +++ b/include/uapi/linux/iommu.h
> @@ -332,4 +332,63 @@ struct iommu_gpasid_bind_data {
> } vendor;
> };
>
> +/*
> + * struct iommu_nesting_info - Information for nesting-capable IOMMU.
> + * user space should check it before using
> + * nesting capability.
> + *
> + * @size: size of the whole structure
> + * @format: PASID table entry format, the same definition with
> + * @format of struct iommu_gpasid_bind_data.
> + * @features: supported nesting features.
> + * @flags: currently reserved for future extension.
> + * @data: vendor specific cap info.
> + *
> + * +---------------+----------------------------------------------------+
> + * | feature | Notes |
> + * +===============+====================================================+
> + * | SYSWIDE_PASID | Kernel manages PASID in system wide, PASIDs used |
> + * | | in the system should be allocated by host kernel |
> + * +---------------+----------------------------------------------------+
> + * | BIND_PGTBL | bind page tables to host PASID, the PASID could |
> + * | | either be a host PASID passed in bind request or |
> + * | | default PASIDs (e.g. default PASID of aux-domain) |
> + * +---------------+----------------------------------------------------+
> + * | CACHE_INVLD | mandatory feature for nesting capable IOMMU |
> + * +---------------+----------------------------------------------------+
Agree with the previous comments on these descriptions and Kevin's
suggestions.
> + *
> + */
> +struct iommu_nesting_info {
> + __u32 size;
> + __u32 format;
> + __u32 features;
> +#define IOMMU_NESTING_FEAT_SYSWIDE_PASID (1 << 0)
> +#define IOMMU_NESTING_FEAT_BIND_PGTBL (1 << 1)
> +#define IOMMU_NESTING_FEAT_CACHE_INVLD (1 << 2)
> + __u32 flags;
> + __u8 data[];
How does the user determine which vendor structure is provided in
data[]? Thanks,
Alex
> +};
> +
> +/*
> + * struct iommu_nesting_info_vtd - Intel VT-d specific nesting info
> + *
> + *
> + * @flags: VT-d specific flags. Currently reserved for future
> + * extension.
> + * @addr_width: The output addr width of first level/stage translation
> + * @pasid_bits: Maximum supported PASID bits, 0 represents no PASID
> + * support.
> + * @cap_reg: Describe basic capabilities as defined in VT-d capability
> + * register.
> + * @ecap_reg: Describe the extended capabilities as defined in VT-d
> + * extended capability register.
> + */
> +struct iommu_nesting_info_vtd {
> + __u32 flags;
> + __u16 addr_width;
> + __u16 pasid_bits;
> + __u64 cap_reg;
> + __u64 ecap_reg;
> +};
> +
> #endif /* _UAPI_IOMMU_H */
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