[PATCH v5 14/24] iommu/amd: Add per-VM private IPA alloc/map helpers

[Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>]

Guest device ID and guest domain ID tables use dedicated slots in
the vIOMMU private address (IPA) region, indexed by guest ID (GID).

Add alloc_private_vm_region() and free_private_vm_region() to
allocate backing pages, map them through viommu_pdom, and tear down
with an unmap flush on VM destroy.

Charge GFP_KERNEL_ACCOUNT so the DevID/DomID pages count against
the caller's memcg. iommufd already charges the vIOMMU object.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/viommu.c | 39 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/iommu/amd/viommu.c b/drivers/iommu/amd/viommu.c
index 3ec907a498c2..ad5f754f25a4 100644
--- a/drivers/iommu/amd/viommu.c
+++ b/drivers/iommu/amd/viommu.c
@@ -373,3 +373,42 @@ int __init amd_viommu_init(struct amd_iommu *iommu)
 	amd_viommu_uninit(iommu);
 	return ret;
 }
+
+static int __maybe_unused alloc_private_vm_region(struct amd_iommu *iommu, u64 **entry,
+						 u64 base, size_t size, u16 gid)
+{
+	int ret;
+	void *va = NULL;
+	u64 addr = base + (gid * size);
+
+	/* Charge the caller; boot IPA stays GFP_KERNEL. */
+	ret = viommu_priv_alloc_map(iommu, addr, size, GFP_KERNEL_ACCOUNT, &va);
+	if (ret) {
+		*entry = NULL;
+		return ret;
+	}
+
+	*entry = (u64 *)va;
+
+	pr_debug("%s: entry=%#llx(%#llx), addr=%#llx, size=%#lx\n", __func__,
+		 (unsigned long long)*entry, iommu_virt_to_phys(*entry), addr, size);
+
+	return 0;
+}
+
+static void __maybe_unused free_private_vm_region(struct amd_iommu *iommu, u64 **entry,
+						  u64 base, size_t size, u16 gid)
+{
+	u64 addr = base + (gid * size);
+
+	if (!iommu || !iommu->viommu_pdom || !*entry)
+		return;
+
+	pr_debug("%s: entry=%#llx(%#llx), base=%#llx, addr=%#llx, size=%#lx\n",
+		 __func__, (unsigned long long)*entry,
+		 iommu_virt_to_phys(*entry), base, addr, size);
+
+	viommu_priv_unmap_free(iommu, addr, size, *entry);
+
+	*entry = NULL;
+}
-- 
2.34.1