linux-kernel - [RFC PATCH 08/24] KVM: SEV: Drop pre_sev

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250326193619.3714986-9-yosry.ahmed@linux.dev>
Date: Wed, 26 Mar 2025 19:36:03 +0000
From: Yosry Ahmed <yosry.ahmed@...ux.dev>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>,
	Jim Mattson <jmattson@...gle.com>,
	Maxim Levitsky <mlevitsk@...hat.com>,
	Vitaly Kuznetsov <vkuznets@...hat.com>,
	Rik van Riel <riel@...riel.com>,
	Tom Lendacky <thomas.lendacky@....com>,
	x86@...nel.org,
	kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Yosry Ahmed <yosry.ahmed@...ux.dev>
Subject: [RFC PATCH 08/24] KVM: SEV: Drop pre_sev_run()

Now that the ASID to vCPU/VMCB tracking was moved out of pre_sev_run(),
the only remaining pieces are:
(a) Checking for valid VMSA.
(b) Assigning svm->asid.
(c) Flush the ASID if the VMCB is run on a different physical CPU.

The check in (c) is already being done in pre_svm_run(), and so is
redundant. (a) and (b) are small enough and probably do not warrant a
separate helper (and (b) will be going way soon), so open-code the
function into pre_svm_run() and remove it.

Signed-off-by: Yosry Ahmed <yosry.ahmed@...ux.dev>
---
 arch/x86/kvm/svm/sev.c | 28 ----------------------------
 arch/x86/kvm/svm/svm.c | 16 ++++++++++++++--
 arch/x86/kvm/svm/svm.h |  1 -
 3 files changed, 14 insertions(+), 31 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 3ef0dfdbb34d2..1742f51d4c194 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3451,34 +3451,6 @@ void sev_es_unmap_ghcb(struct vcpu_svm *svm)
 	svm->sev_es.ghcb = NULL;
 }
 
-int pre_sev_run(struct vcpu_svm *svm, int cpu)
-{
-	struct kvm *kvm = svm->vcpu.kvm;
-	unsigned int asid = sev_get_asid(kvm);
-
-	/*
-	 * Reject KVM_RUN if userspace attempts to run the vCPU with an invalid
-	 * VMSA, e.g. if userspace forces the vCPU to be RUNNABLE after an SNP
-	 * AP Destroy event.
-	 */
-	if (sev_es_guest(kvm) && !VALID_PAGE(svm->vmcb->control.vmsa_pa))
-		return -EINVAL;
-
-	/* Assign the asid allocated with this SEV guest */
-	svm->asid = asid;
-
-	/*
-	 * Flush guest TLB if the VMCB was executed on a differet host CPU in
-	 * previous VMRUNs.
-	 */
-	if (svm->vcpu.arch.last_vmentry_cpu == cpu)
-		return 0;
-
-	vmcb_set_flush_asid(svm->vmcb);
-	vmcb_mark_dirty(svm->vmcb, VMCB_ASID);
-	return 0;
-}
-
 #define GHCB_SCRATCH_AREA_LIMIT		(16ULL * PAGE_SIZE)
 static int setup_vmgexit_scratch(struct vcpu_svm *svm, bool sync, u64 len)
 {
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index e6e380411fbec..ce67112732e8c 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3649,8 +3649,20 @@ static int pre_svm_run(struct kvm_vcpu *vcpu)
 		svm->current_vmcb->cpu = vcpu->cpu;
         }
 
-	if (sev_guest(vcpu->kvm))
-		return pre_sev_run(svm, vcpu->cpu);
+	if (sev_guest(vcpu->kvm)) {
+		/* Assign the asid allocated with this SEV guest */
+		svm->asid = sev_get_asid(vcpu->kvm);
+
+		/*
+		 * Reject KVM_RUN if userspace attempts to run the vCPU with an invalid
+		 * VMSA, e.g. if userspace forces the vCPU to be RUNNABLE after an SNP
+		 * AP Destroy event.
+		 */
+		if (sev_es_guest(vcpu->kvm) &&
+		    !VALID_PAGE(svm->vmcb->control.vmsa_pa))
+			return -EINVAL;
+		return 0;
+	}
 
 	/* FIXME: handle wraparound of asid_generation */
 	if (svm->current_vmcb->asid_generation != sd->asid_generation)
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index ca38a233fa24c..3ab2a424992c1 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -760,7 +760,6 @@ void avic_refresh_virtual_apic_mode(struct kvm_vcpu *vcpu);
 
 /* sev.c */
 
-int pre_sev_run(struct vcpu_svm *svm, int cpu);
 void sev_init_vmcb(struct vcpu_svm *svm);
 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);
-- 
2.49.0.395.g12beb8f557-goog