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    SubjectRe: [RFC v3 02/15] vfio: expose MSI mapping requirement through VFIO_IOMMU_GET_INFO
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    Hi Marc,
    On 02/18/2016 10:34 AM, Marc Zyngier wrote:
    > On Fri, 12 Feb 2016 08:13:04 +0000
    > Eric Auger <eric.auger@linaro.org> wrote:
    >
    >> This patch allows the user-space to retrieve whether msi write
    >> transaction addresses must be mapped. This is returned through the
    >> VFIO_IOMMU_GET_INFO API and its new flag: VFIO_IOMMU_INFO_REQUIRE_MSI_MAP.
    >>
    >> Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
    >> Signed-off-by: Eric Auger <eric.auger@linaro.org>
    >>
    >> ---
    >>
    >> RFC v1 -> v1:
    >> - derived from
    >> [RFC PATCH 3/6] vfio: Extend iommu-info to return MSIs automap state
    >> - renamed allow_msi_reconfig into require_msi_mapping
    >> - fixed VFIO_IOMMU_GET_INFO
    >> ---
    >> drivers/vfio/vfio_iommu_type1.c | 26 ++++++++++++++++++++++++++
    >> include/uapi/linux/vfio.h | 1 +
    >> 2 files changed, 27 insertions(+)
    >>
    >> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
    >> index 6f1ea3d..c5b57e1 100644
    >> --- a/drivers/vfio/vfio_iommu_type1.c
    >> +++ b/drivers/vfio/vfio_iommu_type1.c
    >> @@ -255,6 +255,29 @@ static int vaddr_get_pfn(unsigned long vaddr, int prot, unsigned long *pfn)
    >> }
    >>
    >> /*
    >> + * vfio_domains_require_msi_mapping: indicates whether MSI write transaction
    >> + * addresses must be mapped
    >> + *
    >> + * returns true if it does
    >> + */
    >> +static bool vfio_domains_require_msi_mapping(struct vfio_iommu *iommu)
    >> +{
    >> + struct vfio_domain *d;
    >> + bool ret;
    >> +
    >> + mutex_lock(&iommu->lock);
    >> + /* All domains have same require_msi_map property, pick first */
    >> + d = list_first_entry(&iommu->domain_list, struct vfio_domain, next);
    >> + if (iommu_domain_get_attr(d->domain, DOMAIN_ATTR_MSI_MAPPING, NULL) < 0)
    >> + ret = false;
    >> + else
    >> + ret = true;
    >
    > nit: this could be simplified as:
    >
    > ret = (iommu_domain_get_attr(d->domain, DOMAIN_ATTR_MSI_MAPPING, NULL) == 0);
    sure ;-)
    >
    >> + mutex_unlock(&iommu->lock);
    >> +
    >> + return ret;
    >> +}
    >> +
    >> +/*
    >> * Attempt to pin pages. We really don't want to track all the pfns and
    >> * the iommu can only map chunks of consecutive pfns anyway, so get the
    >> * first page and all consecutive pages with the same locking.
    >> @@ -997,6 +1020,9 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
    >>
    >> info.flags = VFIO_IOMMU_INFO_PGSIZES;
    >>
    >> + if (vfio_domains_require_msi_mapping(iommu))
    >> + info.flags |= VFIO_IOMMU_INFO_REQUIRE_MSI_MAP;
    >> +
    >> info.iova_pgsizes = vfio_pgsize_bitmap(iommu);
    >>
    >> return copy_to_user((void __user *)arg, &info, minsz);
    >> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
    >> index 7d7a4c6..43e183b 100644
    >> --- a/include/uapi/linux/vfio.h
    >> +++ b/include/uapi/linux/vfio.h
    >> @@ -400,6 +400,7 @@ struct vfio_iommu_type1_info {
    >> __u32 argsz;
    >> __u32 flags;
    >> #define VFIO_IOMMU_INFO_PGSIZES (1 << 0) /* supported page sizes info */
    >> +#define VFIO_IOMMU_INFO_REQUIRE_MSI_MAP (1 << 1)/* MSI must be mapped */
    >> __u64 iova_pgsizes; /* Bitmap of supported page sizes */
    >> };
    >>
    >
    >
    > FWIW:
    >
    > Acked-by: Marc Zyngier <marc.zyngier@arm.com>
    thanks

    Eric
    >
    > M.
    >

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