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

[Sasha Levin <sashal@kernel.org>]

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