FAILED: patch "[PATCH] KVM: SEV: Extract loading of guest-provided VMSA to a" failed to apply to 6.12-stable tree

FAILED: patch "[PATCH] KVM: SEV: Extract loading of guest-provided VMSA to a" failed to apply to 6.12-stable tree

[gregkh]

The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 0060569e4f18a7dee2dd8728595e909f19a23c24
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026083120-cilantro-legacy-9d5a@gregkh' --subject-prefix 'PATCH 6.12.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0060569e4f18a7dee2dd8728595e909f19a23c24 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@google.com>
Date: Thu, 9 Jul 2026 13:49:32 -0700
Subject: [PATCH] KVM: SEV: Extract loading of guest-provided VMSA to a
 separate helper

Extract the loading/retrieval of a guest-provided VMSA to a separate helper
so that KVM can reuse the core logic when refreshing the VMSA after an MMU
invalidation from guest_memfd.

No functional change intended.

Cc: stable@vger.kernel.org # 6.12.x
Reviewed-by: Michael Roth <michael.roth@amd.com>
Link: https://patch.msgid.link/20260709204948.1988414-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 827f5dc06102..d8ed00f76aa3 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3979,29 +3979,17 @@ static int snp_begin_psc(struct vcpu_svm *svm)
 	return snp_do_psc(svm);
 }
 
-/*
- * Invoked as part of svm_vcpu_reset() processing of an init event.
- */
-static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
+static void sev_snp_reload_vmsa(struct kvm_vcpu *vcpu, gpa_t gpa)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct kvm_memory_slot *slot;
+	gfn_t gfn = gpa_to_gfn(gpa);
 	struct page *page;
 	kvm_pfn_t pfn;
-	gfn_t gfn;
 
-	guard(mutex)(&svm->sev_es.snp_vmsa_mutex);
+	lockdep_assert_held(&svm->sev_es.snp_vmsa_mutex);
 
-	if (!svm->sev_es.snp_ap_waiting_for_reset)
-		return;
-
-	svm->sev_es.snp_ap_waiting_for_reset = false;
-
-	/* Mark the vCPU as offline and not runnable */
-	vcpu->arch.pv.pv_unhalted = false;
-	kvm_set_mp_state(vcpu, KVM_MP_STATE_HALTED);
-
-	/* Clear use of the VMSA */
+	/* Clear use of the VMSA. */
 	svm->vmcb->control.vmsa_pa = INVALID_PAGE;
 	svm->sev_es.snp_guest_vmsa_gpa = INVALID_PAGE;
 
@@ -4011,12 +3999,9 @@ static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
 	 */
 	vmcb_mark_all_dirty(svm->vmcb);
 
-	if (!VALID_PAGE(svm->sev_es.snp_pending_vmsa_gpa))
+	if (!VALID_PAGE(gpa))
 		return;
 
-	gfn = gpa_to_gfn(svm->sev_es.snp_pending_vmsa_gpa);
-	svm->sev_es.snp_pending_vmsa_gpa = INVALID_PAGE;
-
 	slot = gfn_to_memslot(vcpu->kvm, gfn);
 	if (!slot)
 		return;
@@ -4040,7 +4025,7 @@ static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
 	svm->sev_es.snp_has_guest_vmsa = true;
 
 	/* Use the new VMSA */
-	svm->sev_es.snp_guest_vmsa_gpa = gfn_to_gpa(gfn);
+	svm->sev_es.snp_guest_vmsa_gpa = gpa;
 	svm->vmcb->control.vmsa_pa = pfn_to_hpa(pfn);
 
 	/* Mark the vCPU as runnable */
@@ -4054,6 +4039,31 @@ static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
 	kvm_release_page_clean(page);
 }
 
+/*
+ * Invoked as part of svm_vcpu_reset() processing of an init event.
+ */
+static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
+{
+	struct vcpu_svm *svm = to_svm(vcpu);
+	gpa_t gpa;
+
+	guard(mutex)(&svm->sev_es.snp_vmsa_mutex);
+
+	if (!svm->sev_es.snp_ap_waiting_for_reset)
+		return;
+
+	svm->sev_es.snp_ap_waiting_for_reset = false;
+
+	/* Mark the vCPU as offline and not runnable */
+	vcpu->arch.pv.pv_unhalted = false;
+	kvm_set_mp_state(vcpu, KVM_MP_STATE_HALTED);
+
+	gpa = svm->sev_es.snp_pending_vmsa_gpa;
+	svm->sev_es.snp_pending_vmsa_gpa = INVALID_PAGE;
+
+	sev_snp_reload_vmsa(vcpu, gpa);
+}
+
 static int sev_snp_ap_creation(struct vcpu_svm *svm)
 {
 	struct kvm_sev_info *sev = to_kvm_sev_info(svm->vcpu.kvm);

[PATCH 6.12.y 1/4] KVM: SEV: Make it more obvious when KVM is writing back the current PSC index

[Sasha Levin]

From: Sean Christopherson <seanjc@google.com>

[ Upstream commit 17d62e0b157f262dd8c7586cb882ece72a5b10c2 ]

Increment the guest-visible "cur_entry" index outside of the for-loop
when processing Page State Change entries, and add a comment to make it
more obvious which code is operating on trusted data, and which code is
touching guest-accessible data.

No functional change intended.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260501202250.2115252-12-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20260529183549.1104619-12-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Stable-dep-of: 0060569e4f18 ("KVM: SEV: Extract loading of guest-provided VMSA to a separate helper")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kvm/svm/sev.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index a6971cd236bed..e5587675cf9ec 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3821,7 +3821,7 @@ static int snp_begin_psc(struct vcpu_svm *svm)
 	}
 
 	/* Find the start of the next range which needs processing. */
-	for (idx = idx_start; idx <= idx_end; idx++, hdr->cur_entry++) {
+	for (idx = idx_start; idx <= idx_end; idx++) {
 		entry_start = READ_ONCE(entries[idx]);
 
 		gfn = entry_start.gfn;
@@ -3848,6 +3848,14 @@ static int snp_begin_psc(struct vcpu_svm *svm)
 
 		if (npages)
 			break;
+
+		/*
+		 * Increment the guest-visible index to communicate the current
+		 * entry back to the guest, e.g. in case of failure.  No need
+		 * for READ_ONCE() as KVM doesn't consume the field, i.e. a
+		 * misbehaving guest can only break itself.
+		 */
+		hdr->cur_entry++;
 	}
 
 	if (idx > idx_end) {
-- 
2.53.0

[PATCH 6.12.y 2/4] KVM: SEV: Add an anonymous "psc" struct to track current PSC metadata

[Sasha Levin]

From: Sean Christopherson <seanjc@google.com>

[ Upstream commit 00b9744a3688758c5c492756d08a1cd599a76965 ]

Add a "psc" struct to vcpu_sev_es_state to avoid having to prefix all of
the fields with "psc_".

Take advantage of the code churn to opportunistically rename local
variables to "guest_psc" to make it more obvious that the buffer is guest
data, and more importantly, guest accessible!

Opportunistically rename inflight => batch_size as well, because there can
really only be one operation in-flight (per-vCPU), i.e. "inflight" _looks_
like a boolean, but in actuality is an integer tracking how many pages are
being handled by the current operation.

No functional change intended.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260501202250.2115252-13-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20260529183549.1104619-13-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Stable-dep-of: 0060569e4f18 ("KVM: SEV: Extract loading of guest-provided VMSA to a separate helper")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kvm/svm/sev.c | 43 +++++++++++++++++++-----------------------
 arch/x86/kvm/svm/svm.h |  8 +++++---
 2 files changed, 24 insertions(+), 27 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index e5587675cf9ec..a5a4e60f85c69 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3726,17 +3726,14 @@ static int snp_begin_psc(struct vcpu_svm *svm);
 
 static void snp_complete_psc(struct vcpu_svm *svm, u64 psc_ret)
 {
-	svm->sev_es.psc_inflight = 0;
-	svm->sev_es.psc_idx = 0;
-	svm->sev_es.psc_2m = false;
+	memset(&svm->sev_es.psc, 0, sizeof(svm->sev_es.psc));
 	ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, psc_ret);
 }
 
 static void __snp_complete_one_psc(struct vcpu_svm *svm)
 {
-	struct psc_buffer *psc = svm->sev_es.ghcb_sa;
-	struct psc_entry *entries = psc->entries;
-	struct psc_hdr *hdr = &psc->hdr;
+	struct vcpu_sev_es_state *sev_es = &svm->sev_es;
+	struct psc_buffer *guest_psc = sev_es->ghcb_sa;
 	__u16 idx;
 
 	/*
@@ -3744,14 +3741,14 @@ static void __snp_complete_one_psc(struct vcpu_svm *svm)
 	 * corresponding entries in the guest's PSC buffer and zero out the
 	 * count of in-flight PSC entries.
 	 */
-	for (idx = svm->sev_es.psc_idx; svm->sev_es.psc_inflight;
-	     svm->sev_es.psc_inflight--, idx++) {
-		struct psc_entry entry = READ_ONCE(entries[idx]);
+	for (idx = sev_es->psc.cur_idx; sev_es->psc.batch_size;
+	     sev_es->psc.batch_size--, idx++) {
+		struct psc_entry entry = READ_ONCE(guest_psc->entries[idx]);
 
-		entries[idx].cur_page = entry.pagesize ? 512 : 1;
+		guest_psc->entries[idx].cur_page = entry.pagesize ? 512 : 1;
 	}
 
-	hdr->cur_entry = idx;
+	guest_psc->hdr.cur_entry = idx;
 }
 
 static int snp_complete_one_psc(struct kvm_vcpu *vcpu)
@@ -3772,10 +3769,8 @@ static int snp_complete_one_psc(struct kvm_vcpu *vcpu)
 static int snp_begin_psc(struct vcpu_svm *svm)
 {
 	struct vcpu_sev_es_state *sev_es = &svm->sev_es;
-	struct psc_buffer *psc = sev_es->ghcb_sa;
-	struct psc_entry *entries = psc->entries;
+	struct psc_buffer *guest_psc = sev_es->ghcb_sa;
 	struct kvm_vcpu *vcpu = &svm->vcpu;
-	struct psc_hdr *hdr = &psc->hdr;
 	struct psc_entry entry_start;
 	u16 idx, idx_start, idx_end, max_nr_entries;
 	int npages;
@@ -3802,7 +3797,7 @@ static int snp_begin_psc(struct vcpu_svm *svm)
 
 next_range:
 	/* There should be no other PSCs in-flight at this point. */
-	if (WARN_ON_ONCE(svm->sev_es.psc_inflight)) {
+	if (WARN_ON_ONCE(svm->sev_es.psc.batch_size)) {
 		snp_complete_psc(svm, VMGEXIT_PSC_ERROR_GENERIC);
 		return 1;
 	}
@@ -3812,8 +3807,8 @@ static int snp_begin_psc(struct vcpu_svm *svm)
 	 * validation, so take care to only use validated copies of values used
 	 * for things like array indexing.
 	 */
-	idx_start = READ_ONCE(hdr->cur_entry);
-	idx_end = READ_ONCE(hdr->end_entry);
+	idx_start = READ_ONCE(guest_psc->hdr.cur_entry);
+	idx_end = READ_ONCE(guest_psc->hdr.end_entry);
 
 	if (idx_end >= max_nr_entries) {
 		snp_complete_psc(svm, VMGEXIT_PSC_ERROR_INVALID_HDR);
@@ -3822,7 +3817,7 @@ static int snp_begin_psc(struct vcpu_svm *svm)
 
 	/* Find the start of the next range which needs processing. */
 	for (idx = idx_start; idx <= idx_end; idx++) {
-		entry_start = READ_ONCE(entries[idx]);
+		entry_start = READ_ONCE(guest_psc->entries[idx]);
 
 		gfn = entry_start.gfn;
 		huge = entry_start.pagesize;
@@ -3855,7 +3850,7 @@ static int snp_begin_psc(struct vcpu_svm *svm)
 		 * for READ_ONCE() as KVM doesn't consume the field, i.e. a
 		 * misbehaving guest can only break itself.
 		 */
-		hdr->cur_entry++;
+		guest_psc->hdr.cur_entry++;
 	}
 
 	if (idx > idx_end) {
@@ -3864,9 +3859,9 @@ static int snp_begin_psc(struct vcpu_svm *svm)
 		return 1;
 	}
 
-	svm->sev_es.psc_2m = huge;
-	svm->sev_es.psc_idx = idx;
-	svm->sev_es.psc_inflight = 1;
+	sev_es->psc.is_2m = huge;
+	sev_es->psc.cur_idx = idx;
+	sev_es->psc.batch_size = 1;
 
 	/*
 	 * Find all subsequent PSC entries that contain adjacent GPA
@@ -3874,14 +3869,14 @@ static int snp_begin_psc(struct vcpu_svm *svm)
 	 * KVM_HC_MAP_GPA_RANGE exit.
 	 */
 	while (++idx <= idx_end) {
-		struct psc_entry entry = READ_ONCE(entries[idx]);
+		struct psc_entry entry = READ_ONCE(guest_psc->entries[idx]);
 
 		if (entry.operation != entry_start.operation ||
 		    entry.gfn != entry_start.gfn + npages ||
 		    entry.cur_page || !!entry.pagesize != huge)
 			break;
 
-		svm->sev_es.psc_inflight++;
+		sev_es->psc.batch_size++;
 		npages += huge ? 512 : 1;
 	}
 
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index c34cd7f1408fc..c7920968a0dd5 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -231,9 +231,11 @@ struct vcpu_sev_es_state {
 	bool ghcb_sa_free;
 
 	/* SNP Page-State-Change buffer entries currently being processed */
-	u16 psc_idx;
-	u16 psc_inflight;
-	bool psc_2m;
+	struct {
+		u16 cur_idx;
+		u16 batch_size;
+		bool is_2m;
+	} psc;
 
 	u64 ghcb_registered_gpa;
 
-- 
2.53.0

[PATCH 6.12.y 3/4] KVM: SEV: Read start/end indices of PSC requests exactly once per #VMGEXIT

[Sasha Levin]

From: Sean Christopherson <seanjc@google.com>

[ Upstream commit ce6ea7b33e0075335b1eb3b227a21a98e3196e41 ]

Rework Page State Change (PSC) handling to read the guest-provided start
and end indices exactly once, at the beginning of the request.  Re-reading
the indices is "fine", _if_ the guest is well-behaved.  KVM _should_ be
safe against concurrent guest modification of the indices, but there is
zero reason to introduce unnecessary risk.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260501202250.2115252-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20260529183549.1104619-14-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Stable-dep-of: 0060569e4f18 ("KVM: SEV: Extract loading of guest-provided VMSA to a separate helper")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kvm/svm/sev.c | 223 +++++++++++++++++++++--------------------
 arch/x86/kvm/svm/svm.c |  11 +-
 arch/x86/kvm/svm/svm.h |   8 +-
 3 files changed, 125 insertions(+), 117 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index a5a4e60f85c69..5bf1295844643 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2033,7 +2033,7 @@ static void sev_migrate_from(struct kvm *dst_kvm, struct kvm *src_kvm)
 	kvm_for_each_vcpu(i, dst_vcpu, dst_kvm) {
 		dst_svm = to_svm(dst_vcpu);
 
-		sev_init_vmcb(dst_svm);
+		sev_init_vmcb(dst_svm, false);
 
 		if (!dst->es_active)
 			continue;
@@ -3722,7 +3722,17 @@ struct psc_buffer {
 	struct psc_entry entries[];
 } __packed;
 
-static int snp_begin_psc(struct vcpu_svm *svm);
+/* Compatibility shims for the post-6.12 VMSA helpers. */
+#define kvm_set_mp_state(vcpu, state) ((vcpu)->arch.mp_state = (state))
+#define kvm_gmem_get_pfn(kvm, slot, gfn, pfn, page, order)		\
+({									\
+	int __ret = kvm_gmem_get_pfn(kvm, slot, gfn, pfn, order);	\
+	if (!__ret)							\
+		*(page) = pfn_to_page(*(pfn));				\
+	__ret;								\
+})
+
+static int snp_do_psc(struct vcpu_svm *svm);
 
 static void snp_complete_psc(struct vcpu_svm *svm, u64 psc_ret)
 {
@@ -3748,6 +3758,7 @@ static void __snp_complete_one_psc(struct vcpu_svm *svm)
 		guest_psc->entries[idx].cur_page = entry.pagesize ? 512 : 1;
 	}
 
+	sev_es->psc.cur_idx = idx;
 	guest_psc->hdr.cur_entry = idx;
 }
 
@@ -3763,37 +3774,19 @@ static int snp_complete_one_psc(struct kvm_vcpu *vcpu)
 	__snp_complete_one_psc(svm);
 
 	/* Handle the next range (if any). */
-	return snp_begin_psc(svm);
+	return snp_do_psc(svm);
 }
 
-static int snp_begin_psc(struct vcpu_svm *svm)
+static int snp_do_psc(struct vcpu_svm *svm)
 {
 	struct vcpu_sev_es_state *sev_es = &svm->sev_es;
 	struct psc_buffer *guest_psc = sev_es->ghcb_sa;
 	struct kvm_vcpu *vcpu = &svm->vcpu;
 	struct psc_entry entry_start;
-	u16 idx, idx_start, idx_end, max_nr_entries;
 	int npages;
 	bool huge;
 	u64 gfn;
-
-	if (!(vcpu->kvm->arch.hypercall_exit_enabled & (1 << KVM_HC_MAP_GPA_RANGE))) {
-		snp_complete_psc(svm, VMGEXIT_PSC_ERROR_GENERIC);
-		return 1;
-	}
-
-	/*
-	 * GHCB v2 requires the scratch area to reside within the GHCB itself,
-	 * and PSC requests are only supported for GHCB v2+.  Thus it should be
-	 * impossible to exceed the max PSC entry count (which is derived from
-	 * the size of the shared GHCB buffer).
-	 */
-	max_nr_entries = (sev_es->ghcb_sa_len - sizeof(struct psc_hdr)) /
-			 sizeof(struct psc_entry);
-	if (WARN_ON_ONCE(max_nr_entries > VMGEXIT_PSC_MAX_COUNT)) {
-		snp_complete_psc(svm, VMGEXIT_PSC_ERROR_GENERIC);
-		return 1;
-	}
+	u16 idx;
 
 next_range:
 	/* There should be no other PSCs in-flight at this point. */
@@ -3802,21 +3795,8 @@ static int snp_begin_psc(struct vcpu_svm *svm)
 		return 1;
 	}
 
-	/*
-	 * The PSC descriptor buffer can be modified by a misbehaved guest after
-	 * validation, so take care to only use validated copies of values used
-	 * for things like array indexing.
-	 */
-	idx_start = READ_ONCE(guest_psc->hdr.cur_entry);
-	idx_end = READ_ONCE(guest_psc->hdr.end_entry);
-
-	if (idx_end >= max_nr_entries) {
-		snp_complete_psc(svm, VMGEXIT_PSC_ERROR_INVALID_HDR);
-		return 1;
-	}
-
 	/* Find the start of the next range which needs processing. */
-	for (idx = idx_start; idx <= idx_end; idx++) {
+	for (idx = sev_es->psc.cur_idx; idx <= sev_es->psc.end_idx; idx++) {
 		entry_start = READ_ONCE(guest_psc->entries[idx]);
 
 		gfn = entry_start.gfn;
@@ -3853,7 +3833,7 @@ static int snp_begin_psc(struct vcpu_svm *svm)
 		guest_psc->hdr.cur_entry++;
 	}
 
-	if (idx > idx_end) {
+	if (idx > sev_es->psc.end_idx) {
 		/* Nothing more to process. */
 		snp_complete_psc(svm, 0);
 		return 1;
@@ -3868,7 +3848,7 @@ static int snp_begin_psc(struct vcpu_svm *svm)
 	 * ranges/operations and can be combined into a single
 	 * KVM_HC_MAP_GPA_RANGE exit.
 	 */
-	while (++idx <= idx_end) {
+	while (++idx <= sev_es->psc.end_idx) {
 		struct psc_entry entry = READ_ONCE(guest_psc->entries[idx]);
 
 		if (entry.operation != entry_start.operation ||
@@ -3911,63 +3891,72 @@ static int snp_begin_psc(struct vcpu_svm *svm)
 	BUG();
 }
 
-static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)
+static int snp_begin_psc(struct vcpu_svm *svm)
 {
-	struct vcpu_svm *svm = to_svm(vcpu);
+	struct vcpu_sev_es_state *sev_es = &svm->sev_es;
+	struct psc_buffer *guest_psc = sev_es->ghcb_sa;
+	u16 max_nr_entries;
 
-	WARN_ON(!mutex_is_locked(&svm->sev_es.snp_vmsa_mutex));
+	if (!(svm->vcpu.kvm->arch.hypercall_exit_enabled &
+	      (1 << KVM_HC_MAP_GPA_RANGE))) {
+		snp_complete_psc(svm, VMGEXIT_PSC_ERROR_GENERIC);
+		return 1;
+	}
 
-	/* Mark the vCPU as offline and not runnable */
-	vcpu->arch.pv.pv_unhalted = false;
-	vcpu->arch.mp_state = KVM_MP_STATE_HALTED;
+	/*
+	 * GHCB v2 requires the scratch area to reside within the GHCB itself,
+	 * and PSC requests are only supported for GHCB v2+.  Thus it should be
+	 * impossible to exceed the max PSC entry count (which is derived from
+	 * the size of the shared GHCB buffer).
+	 */
+	max_nr_entries = (sev_es->ghcb_sa_len - sizeof(struct psc_hdr)) /
+			 sizeof(struct psc_entry);
+	if (WARN_ON_ONCE(max_nr_entries > VMGEXIT_PSC_MAX_COUNT)) {
+		snp_complete_psc(svm, VMGEXIT_PSC_ERROR_GENERIC);
+		return 1;
+	}
 
-	/* Clear use of the VMSA */
-	svm->vmcb->control.vmsa_pa = INVALID_PAGE;
+	/*
+	 * The PSC descriptor buffer can be modified by a misbehaved guest after
+	 * validation, so take care to only use validated copies of values used
+	 * for things like array indexing.
+	 */
+	sev_es->psc.cur_idx = READ_ONCE(guest_psc->hdr.cur_entry);
+	sev_es->psc.end_idx = READ_ONCE(guest_psc->hdr.end_entry);
 
-	if (VALID_PAGE(svm->sev_es.snp_vmsa_gpa)) {
-		gfn_t gfn = gpa_to_gfn(svm->sev_es.snp_vmsa_gpa);
-		struct kvm_memory_slot *slot;
-		kvm_pfn_t pfn;
+	if (sev_es->psc.end_idx >= max_nr_entries) {
+		snp_complete_psc(svm, VMGEXIT_PSC_ERROR_INVALID_HDR);
+		return 1;
+	}
 
-		slot = gfn_to_memslot(vcpu->kvm, gfn);
-		if (!slot)
-			return -EINVAL;
+	return snp_do_psc(svm);
+}
 
-		/*
-		 * The new VMSA will be private memory guest memory, so
-		 * retrieve the PFN from the gmem backend.
-		 */
-		if (kvm_gmem_get_pfn(vcpu->kvm, slot, gfn, &pfn, NULL))
-			return -EINVAL;
+/*
+ * Invoked as part of svm_vcpu_reset() processing of an init event.
+ */
+static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
+{
+	struct vcpu_svm *svm = to_svm(vcpu);
+	struct kvm_memory_slot *slot;
+	struct page *page;
+	kvm_pfn_t pfn;
+	gfn_t gfn;
 
-		/*
-		 * From this point forward, the VMSA will always be a
-		 * guest-mapped page rather than the initial one allocated
-		 * by KVM in svm->sev_es.vmsa. In theory, svm->sev_es.vmsa
-		 * could be free'd and cleaned up here, but that involves
-		 * cleanups like wbinvd_on_all_cpus() which would ideally
-		 * be handled during teardown rather than guest boot.
-		 * Deferring that also allows the existing logic for SEV-ES
-		 * VMSAs to be re-used with minimal SNP-specific changes.
-		 */
-		svm->sev_es.snp_has_guest_vmsa = true;
+	guard(mutex)(&svm->sev_es.snp_vmsa_mutex);
 
-		/* Use the new VMSA */
-		svm->vmcb->control.vmsa_pa = pfn_to_hpa(pfn);
+	if (!svm->sev_es.snp_ap_waiting_for_reset)
+		return;
 
-		/* Mark the vCPU as runnable */
-		vcpu->arch.pv.pv_unhalted = false;
-		vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
+	svm->sev_es.snp_ap_waiting_for_reset = false;
 
-		svm->sev_es.snp_vmsa_gpa = INVALID_PAGE;
+	/* Mark the vCPU as offline and not runnable */
+	vcpu->arch.pv.pv_unhalted = false;
+	kvm_set_mp_state(vcpu, KVM_MP_STATE_HALTED);
 
-		/*
-		 * gmem pages aren't currently migratable, but if this ever
-		 * changes then care should be taken to ensure
-		 * svm->sev_es.vmsa is pinned through some other means.
-		 */
-		kvm_release_pfn_clean(pfn);
-	}
+	/* Clear use of the VMSA */
+	svm->vmcb->control.vmsa_pa = INVALID_PAGE;
+	svm->sev_es.snp_guest_vmsa_gpa = INVALID_PAGE;
 
 	/*
 	 * When replacing the VMSA during SEV-SNP AP creation,
@@ -3975,38 +3964,52 @@ static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)
 	 */
 	vmcb_mark_all_dirty(svm->vmcb);
 
-	return 0;
-}
+	if (!VALID_PAGE(svm->sev_es.snp_pending_vmsa_gpa))
+		return;
 
-/*
- * Invoked as part of svm_vcpu_reset() processing of an init event.
- */
-void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
-{
-	struct vcpu_svm *svm = to_svm(vcpu);
-	int ret;
+	gfn = gpa_to_gfn(svm->sev_es.snp_pending_vmsa_gpa);
+	svm->sev_es.snp_pending_vmsa_gpa = INVALID_PAGE;
 
-	if (!sev_snp_guest(vcpu->kvm))
+	slot = gfn_to_memslot(vcpu->kvm, gfn);
+	if (!slot)
 		return;
 
-	mutex_lock(&svm->sev_es.snp_vmsa_mutex);
+	/*
+	 * The new VMSA will be private memory guest memory, so retrieve the
+	 * PFN from the gmem backend.
+	 */
+	if (kvm_gmem_get_pfn(vcpu->kvm, slot, gfn, &pfn, &page, NULL))
+		return;
 
-	if (!svm->sev_es.snp_ap_waiting_for_reset)
-		goto unlock;
+	/*
+	 * From this point forward, the VMSA will always be a guest-mapped page
+	 * rather than the initial one allocated by KVM in svm->sev_es.vmsa. In
+	 * theory, svm->sev_es.vmsa could be free'd and cleaned up here, but
+	 * that involves cleanups like flushing caches, which would ideally be
+	 * handled during teardown rather than guest boot.  Deferring that also
+	 * allows the existing logic for SEV-ES VMSAs to be re-used with
+	 * minimal SNP-specific changes.
+	 */
+	svm->sev_es.snp_has_guest_vmsa = true;
 
-	svm->sev_es.snp_ap_waiting_for_reset = false;
+	/* Use the new VMSA */
+	svm->sev_es.snp_guest_vmsa_gpa = gfn_to_gpa(gfn);
+	svm->vmcb->control.vmsa_pa = pfn_to_hpa(pfn);
 
-	ret = __sev_snp_update_protected_guest_state(vcpu);
-	if (ret)
-		vcpu_unimpl(vcpu, "snp: AP state update on init failed\n");
+	/* Mark the vCPU as runnable */
+	kvm_set_mp_state(vcpu, KVM_MP_STATE_RUNNABLE);
 
-unlock:
-	mutex_unlock(&svm->sev_es.snp_vmsa_mutex);
+	/*
+	 * gmem pages aren't currently migratable, but if this ever changes
+	 * then care should be taken to ensure svm->sev_es.vmsa is pinned
+	 * through some other means.
+	 */
+	kvm_release_page_clean(page);
 }
 
 static int sev_snp_ap_creation(struct vcpu_svm *svm)
 {
-	struct kvm_sev_info *sev = &to_kvm_svm(svm->vcpu.kvm)->sev_info;
+	struct kvm_sev_info *sev = to_kvm_sev_info(svm->vcpu.kvm);
 	struct kvm_vcpu *vcpu = &svm->vcpu;
 	struct kvm_vcpu *target_vcpu;
 	struct vcpu_svm *target_svm;
@@ -4080,10 +4083,10 @@ static int sev_snp_ap_creation(struct vcpu_svm *svm)
 			goto out;
 		}
 
-		target_svm->sev_es.snp_vmsa_gpa = svm->vmcb->control.exit_info_2;
+		target_svm->sev_es.snp_pending_vmsa_gpa = svm->vmcb->control.exit_info_2;
 		break;
 	case SVM_VMGEXIT_AP_DESTROY:
-		target_svm->sev_es.snp_vmsa_gpa = INVALID_PAGE;
+		target_svm->sev_es.snp_pending_vmsa_gpa = INVALID_PAGE;
 		break;
 	default:
 		vcpu_unimpl(vcpu, "vmgexit: invalid AP creation request [%#x] from guest\n",
@@ -4105,6 +4108,9 @@ static int sev_snp_ap_creation(struct vcpu_svm *svm)
 	return ret;
 }
 
+#undef kvm_gmem_get_pfn
+#undef kvm_set_mp_state
+
 static int snp_handle_guest_req(struct vcpu_svm *svm, gpa_t req_gpa, gpa_t resp_gpa)
 {
 	struct sev_data_snp_guest_request data = {0};
@@ -4648,7 +4654,7 @@ static void sev_es_init_vmcb(struct vcpu_svm *svm)
 	set_msr_interception(vcpu, svm->msrpm, MSR_IA32_CR_PAT, 1, 1);
 }
 
-void sev_init_vmcb(struct vcpu_svm *svm)
+void sev_init_vmcb(struct vcpu_svm *svm, bool init_event)
 {
 	svm->vmcb->control.nested_ctl |= SVM_NESTED_CTL_SEV_ENABLE;
 	clr_exception_intercept(svm, UD_VECTOR);
@@ -4661,6 +4667,9 @@ void sev_init_vmcb(struct vcpu_svm *svm)
 
 	if (sev_es_guest(svm->vcpu.kvm))
 		sev_es_init_vmcb(svm);
+
+	if (init_event && sev_snp_guest(svm->vcpu.kvm))
+		sev_snp_init_protected_guest_state(&svm->vcpu);
 }
 
 void sev_es_vcpu_reset(struct vcpu_svm *svm)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 44819d9470dcf..f85053b1e4bc5 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1239,7 +1239,7 @@ static inline void init_vmcb_after_set_cpuid(struct kvm_vcpu *vcpu)
 	}
 }
 
-static void init_vmcb(struct kvm_vcpu *vcpu)
+static void init_vmcb(struct kvm_vcpu *vcpu, bool init_event)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct vmcb *vmcb = svm->vmcb01.ptr;
@@ -1378,7 +1378,7 @@ static void init_vmcb(struct kvm_vcpu *vcpu)
 	}
 
 	if (sev_guest(vcpu->kvm))
-		sev_init_vmcb(svm);
+		sev_init_vmcb(svm, init_event);
 
 	svm_hv_init_vmcb(vmcb);
 	init_vmcb_after_set_cpuid(vcpu);
@@ -1414,10 +1414,7 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 	svm->spec_ctrl = 0;
 	svm->virt_spec_ctrl = 0;
 
-	if (init_event)
-		sev_snp_init_protected_guest_state(vcpu);
-
-	init_vmcb(vcpu);
+	init_vmcb(vcpu, init_event);
 
 	if (!init_event)
 		__svm_vcpu_reset(vcpu);
@@ -1473,6 +1470,8 @@ static int svm_vcpu_create(struct kvm_vcpu *vcpu)
 
 	if (vmsa_page)
 		svm->sev_es.vmsa = page_address(vmsa_page);
+	svm->sev_es.snp_pending_vmsa_gpa = INVALID_PAGE;
+	svm->sev_es.snp_guest_vmsa_gpa = INVALID_PAGE;
 
 	svm->guest_state_loaded = false;
 
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index c7920968a0dd5..5b390063e07ae 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -233,6 +233,7 @@ struct vcpu_sev_es_state {
 	/* SNP Page-State-Change buffer entries currently being processed */
 	struct {
 		u16 cur_idx;
+		u16 end_idx;
 		u16 batch_size;
 		bool is_2m;
 	} psc;
@@ -240,7 +241,8 @@ struct vcpu_sev_es_state {
 	u64 ghcb_registered_gpa;
 
 	struct mutex snp_vmsa_mutex; /* Used to handle concurrent updates of VMSA. */
-	gpa_t snp_vmsa_gpa;
+	gpa_t snp_pending_vmsa_gpa;
+	gpa_t snp_guest_vmsa_gpa;
 	bool snp_ap_waiting_for_reset;
 	bool snp_has_guest_vmsa;
 };
@@ -732,7 +734,7 @@ void avic_refresh_virtual_apic_mode(struct kvm_vcpu *vcpu);
 /* sev.c */
 
 void pre_sev_run(struct vcpu_svm *svm, int cpu);
-void sev_init_vmcb(struct vcpu_svm *svm);
+void sev_init_vmcb(struct vcpu_svm *svm, bool init_event);
 void sev_vcpu_after_set_cpuid(struct vcpu_svm *svm);
 int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in);
 void sev_es_vcpu_reset(struct vcpu_svm *svm);
@@ -768,7 +770,6 @@ int sev_cpu_init(struct svm_cpu_data *sd);
 int sev_dev_get_attr(u32 group, u64 attr, u64 *val);
 extern unsigned int max_sev_asid;
 void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code);
-void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu);
 int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order);
 void sev_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end);
 int sev_private_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn);
@@ -792,7 +793,6 @@ static inline int sev_cpu_init(struct svm_cpu_data *sd) { return 0; }
 static inline int sev_dev_get_attr(u32 group, u64 attr, u64 *val) { return -ENXIO; }
 #define max_sev_asid 0
 static inline void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code) {}
-static inline void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu) {}
 static inline int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order)
 {
 	return 0;
-- 
2.53.0

[PATCH 6.12.y 4/4] KVM: SEV: Extract loading of guest-provided VMSA to a separate helper

[Sasha Levin]

From: Sean Christopherson <seanjc@google.com>

[ Upstream commit 0060569e4f18a7dee2dd8728595e909f19a23c24 ]

Extract the loading/retrieval of a guest-provided VMSA to a separate helper
so that KVM can reuse the core logic when refreshing the VMSA after an MMU
invalidation from guest_memfd.

No functional change intended.

Cc: stable@vger.kernel.org # 6.12.x
Reviewed-by: Michael Roth <michael.roth@amd.com>
Link: https://patch.msgid.link/20260709204948.1988414-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kvm/svm/sev.c | 52 +++++++++++++++++++++++++-----------------
 1 file changed, 31 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 5bf1295844643..ba09c75d9aafb 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3932,29 +3932,17 @@ static int snp_begin_psc(struct vcpu_svm *svm)
 	return snp_do_psc(svm);
 }
 
-/*
- * Invoked as part of svm_vcpu_reset() processing of an init event.
- */
-static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
+static void sev_snp_reload_vmsa(struct kvm_vcpu *vcpu, gpa_t gpa)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct kvm_memory_slot *slot;
+	gfn_t gfn = gpa_to_gfn(gpa);
 	struct page *page;
 	kvm_pfn_t pfn;
-	gfn_t gfn;
-
-	guard(mutex)(&svm->sev_es.snp_vmsa_mutex);
-
-	if (!svm->sev_es.snp_ap_waiting_for_reset)
-		return;
 
-	svm->sev_es.snp_ap_waiting_for_reset = false;
-
-	/* Mark the vCPU as offline and not runnable */
-	vcpu->arch.pv.pv_unhalted = false;
-	kvm_set_mp_state(vcpu, KVM_MP_STATE_HALTED);
+	lockdep_assert_held(&svm->sev_es.snp_vmsa_mutex);
 
-	/* Clear use of the VMSA */
+	/* Clear use of the VMSA. */
 	svm->vmcb->control.vmsa_pa = INVALID_PAGE;
 	svm->sev_es.snp_guest_vmsa_gpa = INVALID_PAGE;
 
@@ -3964,12 +3952,9 @@ static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
 	 */
 	vmcb_mark_all_dirty(svm->vmcb);
 
-	if (!VALID_PAGE(svm->sev_es.snp_pending_vmsa_gpa))
+	if (!VALID_PAGE(gpa))
 		return;
 
-	gfn = gpa_to_gfn(svm->sev_es.snp_pending_vmsa_gpa);
-	svm->sev_es.snp_pending_vmsa_gpa = INVALID_PAGE;
-
 	slot = gfn_to_memslot(vcpu->kvm, gfn);
 	if (!slot)
 		return;
@@ -3993,7 +3978,7 @@ static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
 	svm->sev_es.snp_has_guest_vmsa = true;
 
 	/* Use the new VMSA */
-	svm->sev_es.snp_guest_vmsa_gpa = gfn_to_gpa(gfn);
+	svm->sev_es.snp_guest_vmsa_gpa = gpa;
 	svm->vmcb->control.vmsa_pa = pfn_to_hpa(pfn);
 
 	/* Mark the vCPU as runnable */
@@ -4007,6 +3992,31 @@ static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
 	kvm_release_page_clean(page);
 }
 
+/*
+ * Invoked as part of svm_vcpu_reset() processing of an init event.
+ */
+static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu)
+{
+	struct vcpu_svm *svm = to_svm(vcpu);
+	gpa_t gpa;
+
+	guard(mutex)(&svm->sev_es.snp_vmsa_mutex);
+
+	if (!svm->sev_es.snp_ap_waiting_for_reset)
+		return;
+
+	svm->sev_es.snp_ap_waiting_for_reset = false;
+
+	/* Mark the vCPU as offline and not runnable */
+	vcpu->arch.pv.pv_unhalted = false;
+	kvm_set_mp_state(vcpu, KVM_MP_STATE_HALTED);
+
+	gpa = svm->sev_es.snp_pending_vmsa_gpa;
+	svm->sev_es.snp_pending_vmsa_gpa = INVALID_PAGE;
+
+	sev_snp_reload_vmsa(vcpu, gpa);
+}
+
 static int sev_snp_ap_creation(struct vcpu_svm *svm)
 {
 	struct kvm_sev_info *sev = to_kvm_sev_info(svm->vcpu.kvm);
-- 
2.53.0