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Message-ID: <20251021014324.5837-14-suravee.suthikulpanit@amd.com>
Date: Tue, 21 Oct 2025 01:43:21 +0000
From: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To: <jgg@...dia.com>, <nicolinc@...dia.com>
CC: <linux-kernel@...r.kernel.org>, <robin.murphy@....com>, <will@...nel.org>,
<joro@...tes.org>, <kevin.tian@...el.com>, <jsnitsel@...hat.com>,
<vasant.hegde@....com>, <iommu@...ts.linux.dev>, <santosh.shukla@....com>,
<sairaj.arunkodilkar@....com>, <jon.grimm@....com>,
<prashanthpra@...gle.com>, <wvw@...gle.com>, <wnliu@...gle.com>,
<gptran@...gle.com>, <kpsingh@...gle.com>, <joao.m.martins@...cle.com>,
<alejandro.j.jimenez@...cle.com>, Suravee Suthikulpanit
<suravee.suthikulpanit@....com>
Subject: [PATCH v4 13/16] iommu/amd: Track host Domain ID mapping for each guest Domain ID
Each nested domain is assigned guest domain ID (gDomID), which guest OS
programs into guest Device Table Entry (gDTE). For each gDomID, the driver
assigns a corresponding host domain ID (hDomID), which will be programmed
into the host Device Table Entry (hDTE).
The gDTE to hDTE 1:1 mapping is stored in the nest parent domain using
an xarray (struct protection_domain.gdomid_array). When invalidate the
nest parent domain, the INVALIDATE_IOMMU_PAGES must be issued for each
hDomID in the gdomid_array.
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
---
drivers/iommu/amd/amd_iommu_types.h | 3 ++
drivers/iommu/amd/iommu.c | 30 ++++++++++++++++
drivers/iommu/amd/nested.c | 53 ++++++++++++++++++++++++++++-
3 files changed, 85 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index e0f0cd3d34f2..09952b7a256d 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -602,6 +602,7 @@ struct amd_iommu_viommu {
struct nested_domain {
struct iommu_domain domain; /* generic domain handle used by iommu core code */
u16 gdom_id; /* domain ID from gDTE */
+ u16 hdom_id; /* domain ID written to the device table */
struct iommu_hwpt_amd_guest gdte; /* Guest vIOMMU DTE */
struct amd_iommu_viommu *viommu; /* AMD hw-viommu this nested domain belong to */
};
@@ -623,6 +624,8 @@ struct protection_domain {
struct mmu_notifier mn; /* mmu notifier for the SVA domain */
struct list_head dev_data_list; /* List of pdom_dev_data */
+
+ struct xarray gdomid_array; /* gDomID mapping to this nest parent domain */
};
/*
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index c4ff18adcf03..e4db6f304599 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1493,6 +1493,23 @@ static void amd_iommu_flush_tlb_domid(struct amd_iommu *iommu, u32 dom_id)
amd_iommu_completion_wait(iommu);
}
+static int iommu_flush_hdom_ids(struct amd_iommu *iommu,
+ u64 address, size_t size,
+ struct protection_domain *parent)
+{
+ int ret = 0;
+ unsigned long i;
+ struct iommu_cmd cmd;
+ struct nested_domain *ndom;
+
+ xa_for_each(&parent->gdomid_array, i, ndom) {
+ build_inv_iommu_pages(&cmd, address, size, ndom->hdom_id,
+ IOMMU_NO_PASID, false);
+ ret |= iommu_queue_command(iommu, &cmd);
+ }
+ return ret;
+}
+
static void amd_iommu_flush_all(struct amd_iommu *iommu)
{
struct iommu_cmd cmd;
@@ -1639,6 +1656,18 @@ static int domain_flush_pages_v1(struct protection_domain *pdom,
* We need a TLB flush
*/
ret |= iommu_queue_command(pdom_iommu_info->iommu, &cmd);
+
+ /*
+ * A domain w/ v1 table can be a nest parent, which can have
+ * multiple nested domains. Each nested domain has 1:1 mapping
+ * between gDomID and hDomID, which is stored in the gdomid_array.
+ * Therefore, we also need to flush every hDomID associated to this
+ * nest parent domain.
+ *
+ * See drivers/iommu/amd/nested.c: amd_iommu_alloc_domain_nested()
+ */
+ ret |= iommu_flush_hdom_ids(pdom_iommu_info->iommu, address,
+ size, pdom);
}
return ret;
@@ -2470,6 +2499,7 @@ static void protection_domain_init(struct protection_domain *domain)
INIT_LIST_HEAD(&domain->dev_list);
INIT_LIST_HEAD(&domain->dev_data_list);
xa_init(&domain->iommu_array);
+ xa_init(&domain->gdomid_array);
}
struct protection_domain *protection_domain_alloc(void)
diff --git a/drivers/iommu/amd/nested.c b/drivers/iommu/amd/nested.c
index e7b6f69a9d0c..383a3c7b4a91 100644
--- a/drivers/iommu/amd/nested.c
+++ b/drivers/iommu/amd/nested.c
@@ -67,7 +67,7 @@ amd_iommu_alloc_domain_nested(struct iommufd_viommu *viommu, u32 flags,
const struct iommu_user_data *user_data)
{
int ret;
- struct nested_domain *ndom;
+ struct nested_domain *ndom, *curr;
struct amd_iommu_viommu *aviommu = container_of(viommu, struct amd_iommu_viommu, core);
if (user_data->type != IOMMU_HWPT_DATA_AMD_GUEST)
@@ -92,6 +92,49 @@ amd_iommu_alloc_domain_nested(struct iommufd_viommu *viommu, u32 flags,
ndom->domain.type = IOMMU_DOMAIN_NESTED;
ndom->viommu = aviommu;
+ /*
+ * Normally, when a guest has multiple pass-through devices,
+ * the IOMMU driver setup DTEs with the same stage-2 table and
+ * use the same host domain ID (hDomId). In case of nested translation,
+ * if the guest setup different stage-1 tables with same PASID,
+ * IOMMU would use the same TLB tag. This will results in TLB
+ * aliasing issue.
+ *
+ * The guest is assigning gDomIDs based on its own algorithm for managing
+ * cache tags of (DomID, PASID). Within a single viommu, the nest parent domain
+ * (w/ S2 table) is used by all DTEs. But we need to consistently map the gDomID
+ * to a single hDomID. This is done using an xarray in the nest parent domain to
+ * keep track of the gDomID mapping. When the S2 is changed, the INVALIDATE_IOMMU_PAGES
+ * command must be issued for each hDomID in the xarray.
+ *
+ * Since there is no invalidation support and no viommu yet, just always use a
+ * unique hDomID for now.
+ */
+ curr = xa_cmpxchg(&aviommu->parent->gdomid_array,
+ ndom->gdom_id, NULL, ndom, GFP_ATOMIC);
+ if (curr) {
+ if (xa_err(curr)) {
+ ret = -EINVAL;
+ } else {
+ /* The gDomID already exist */
+ pr_debug("%s: Found gdom_id=%#x, hdom_id=%#x\n",
+ __func__, ndom->gdom_id, ndom->hdom_id);
+ ret = -EBUSY;
+ }
+ goto out_err;
+ }
+
+ ndom->hdom_id = amd_iommu_pdom_id_alloc();
+ if (ndom->hdom_id <= 0) {
+ xa_cmpxchg(&aviommu->parent->gdomid_array,
+ ndom->gdom_id, ndom, NULL, GFP_ATOMIC);
+ ret = -ENOSPC;
+ goto out_err;
+ }
+
+ pr_debug("%s: Allocate gdom_id=%#x, hdom_id=%#x\n",
+ __func__, ndom->gdom_id, ndom->hdom_id);
+
return &ndom->domain;
out_err:
kfree(ndom);
@@ -101,7 +144,15 @@ amd_iommu_alloc_domain_nested(struct iommufd_viommu *viommu, u32 flags,
static void nested_domain_free(struct iommu_domain *dom)
{
struct nested_domain *ndom = to_ndomain(dom);
+ struct amd_iommu_viommu *aviommu = ndom->viommu;
+
+ pr_debug("%s: Free gdom_id=%#x, hdom_id=%#x\n",
+ __func__, ndom->gdom_id, ndom->hdom_id);
+
+ xa_cmpxchg(&aviommu->parent->gdomid_array,
+ ndom->gdom_id, ndom, NULL, GFP_ATOMIC);
+ amd_iommu_pdom_id_free(ndom->hdom_id);
kfree(ndom);
}
--
2.34.1
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