iommu: Disambiguate MSI region types

The introduction of reserved regions has left a couple of rough edges
which we could do with sorting out sooner rather than later. Since we
are not yet addressing the potential dynamic aspect of software-managed
reservations and presenting them at arbitrary fixed addresses, it is
incongruous that we end up displaying hardware vs. software-managed MSI
regions to userspace differently, especially since ARM-based systems may
actually require one or the other, or even potentially both at once,
(which iommu-dma currently has no hope of dealing with at all). Let's
resolve the former user-visible inconsistency ASAP before the ABI has
been baked into a kernel release, in a way that also lays the groundwork
for the latter shortcoming to be addressed by follow-up patches.

For clarity, rename the software-managed type to IOMMU_RESV_SW_MSI, use
IOMMU_RESV_MSI to describe the hardware type, and document everything a
little bit. Since the x86 MSI remapping hardware falls squarely under
this meaning of IOMMU_RESV_MSI, apply that type to their regions as well,
so that we tell the same story to userspace across all platforms.

Secondly, as the various region types require quite different handling,
and it really makes little sense to ever try combining them, convert the
bitfield-esque #defines to a plain enum in the process before anyone
gets the wrong impression.

Fixes: d30ddcaa7b02 ("iommu: Add a new type field in iommu_resv_region")
Reviewed-by: Eric Auger <eric.auger@redhat.com>
CC: Alex Williamson <alex.williamson@redhat.com>
CC: David Woodhouse <dwmw2@infradead.org>
CC: kvm@vger.kernel.org
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 98940d1392cb0cd19d648b6a25f2a5ba36c052d4..b17536d6e69bdbf956a61d8c3dff06351a1a51df 100644 (file)
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -3202,7 +3202,7 @@ static void amd_iommu_get_resv_regions(struct device *dev,
 
        region = iommu_alloc_resv_region(MSI_RANGE_START,
                                         MSI_RANGE_END - MSI_RANGE_START + 1,
-                                        0, IOMMU_RESV_RESERVED);
+                                        0, IOMMU_RESV_MSI);
        if (!region)
                return;
        list_add_tail(&region->list, head);

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 5806a6acc94ecd7543c2435558a0907ec0934ff2..591bb96047c9765fd3e0fb536d3f26ca0a5f187f 100644 (file)
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -1888,7 +1888,7 @@ static void arm_smmu_get_resv_regions(struct device *dev,
        int prot = IOMMU_WRITE | IOMMU_NOEXEC | IOMMU_MMIO;
 
        region = iommu_alloc_resv_region(MSI_IOVA_BASE, MSI_IOVA_LENGTH,
-                                        prot, IOMMU_RESV_MSI);
+                                        prot, IOMMU_RESV_SW_MSI);
        if (!region)
                return;
 

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index abf6496843a617070289377ffad3fd1e119b0aa6..b493c99e17f74de338805167c3ddb104e3354b62 100644 (file)
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -1608,7 +1608,7 @@ static void arm_smmu_get_resv_regions(struct device *dev,
        int prot = IOMMU_WRITE | IOMMU_NOEXEC | IOMMU_MMIO;
 
        region = iommu_alloc_resv_region(MSI_IOVA_BASE, MSI_IOVA_LENGTH,
-                                        prot, IOMMU_RESV_MSI);
+                                        prot, IOMMU_RESV_SW_MSI);
        if (!region)
                return;
 

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 91d60493b57cd98eecec66eeee88b51c0e5638f1..d412a313a37232997d406e53379e1466d10b93e7 100644 (file)
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -5249,7 +5249,7 @@ static void intel_iommu_get_resv_regions(struct device *device,
 
        reg = iommu_alloc_resv_region(IOAPIC_RANGE_START,
                                      IOAPIC_RANGE_END - IOAPIC_RANGE_START + 1,
-                                     0, IOMMU_RESV_RESERVED);
+                                     0, IOMMU_RESV_MSI);
        if (!reg)
                return;
        list_add_tail(&reg->list, head);

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 8ea14f41a979fd4e72e3a6093e5fa8d2a0eff24a..3b67144dead2e3811918af8fa44ec6e67a19c955 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -72,6 +72,7 @@ static const char * const iommu_group_resv_type_string[] = {
        [IOMMU_RESV_DIRECT]     = "direct",
        [IOMMU_RESV_RESERVED]   = "reserved",
        [IOMMU_RESV_MSI]        = "msi",
+       [IOMMU_RESV_SW_MSI]     = "msi",
 };
 
 #define IOMMU_GROUP_ATTR(_name, _mode, _show, _store)          \
@@ -1743,8 +1744,8 @@ void iommu_put_resv_regions(struct device *dev, struct list_head *list)
 }
 
 struct iommu_resv_region *iommu_alloc_resv_region(phys_addr_t start,
-                                                 size_t length,
-                                                 int prot, int type)
+                                                 size_t length, int prot,
+                                                 enum iommu_resv_type type)
 {
        struct iommu_resv_region *region;
 

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index c26fa1f3ed8606e65870f05aa47b7eca5fdf381e..32d2633092a37edf64ec4b9d2afc9fa4f12ea77d 100644 (file)
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -1182,8 +1182,7 @@ static struct vfio_group *find_iommu_group(struct vfio_domain *domain,
        return NULL;
 }
 
-static bool vfio_iommu_has_resv_msi(struct iommu_group *group,
-                                   phys_addr_t *base)
+static bool vfio_iommu_has_sw_msi(struct iommu_group *group, phys_addr_t *base)
 {
        struct list_head group_resv_regions;
        struct iommu_resv_region *region, *next;
@@ -1192,7 +1191,7 @@ static bool vfio_iommu_has_resv_msi(struct iommu_group *group,
        INIT_LIST_HEAD(&group_resv_regions);
        iommu_get_group_resv_regions(group, &group_resv_regions);
        list_for_each_entry(region, &group_resv_regions, list) {
-               if (region->type & IOMMU_RESV_MSI) {
+               if (region->type == IOMMU_RESV_SW_MSI) {
                        *base = region->start;
                        ret = true;
                        goto out;
@@ -1283,7 +1282,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
        if (ret)
                goto out_domain;
 
-       resv_msi = vfio_iommu_has_resv_msi(iommu_group, &resv_msi_base);
+       resv_msi = vfio_iommu_has_sw_msi(iommu_group, &resv_msi_base);
 
        INIT_LIST_HEAD(&domain->group_list);
        list_add(&group->next, &domain->group_list);

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 6a6de187ddc0ff1e0e737f94261211b7ea4408e9..2e4de0deee531adbd7c1cd8ff1d25e0d0eb98d47 100644 (file)
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -125,9 +125,16 @@ enum iommu_attr {
 };
 
 /* These are the possible reserved region types */
-#define IOMMU_RESV_DIRECT      (1 << 0)
-#define IOMMU_RESV_RESERVED    (1 << 1)
-#define IOMMU_RESV_MSI         (1 << 2)
+enum iommu_resv_type {
+       /* Memory regions which must be mapped 1:1 at all times */
+       IOMMU_RESV_DIRECT,
+       /* Arbitrary "never map this or give it to a device" address ranges */
+       IOMMU_RESV_RESERVED,
+       /* Hardware MSI region (untranslated) */
+       IOMMU_RESV_MSI,
+       /* Software-managed MSI translation window */
+       IOMMU_RESV_SW_MSI,
+};
 
 /**
  * struct iommu_resv_region - descriptor for a reserved memory region
@@ -142,7 +149,7 @@ struct iommu_resv_region {
        phys_addr_t             start;
        size_t                  length;
        int                     prot;
-       int                     type;
+       enum iommu_resv_type    type;
 };
 
 #ifdef CONFIG_IOMMU_API
@@ -288,7 +295,8 @@ extern void iommu_get_resv_regions(struct device *dev, struct list_head *list);
 extern void iommu_put_resv_regions(struct device *dev, struct list_head *list);
 extern int iommu_request_dm_for_dev(struct device *dev);
 extern struct iommu_resv_region *
-iommu_alloc_resv_region(phys_addr_t start, size_t length, int prot, int type);
+iommu_alloc_resv_region(phys_addr_t start, size_t length, int prot,
+                       enum iommu_resv_type type);
 extern int iommu_get_group_resv_regions(struct iommu_group *group,
                                        struct list_head *head);