linux-kernel - [PATCH 2/2] KVM: x86: Clear pv_unhalted on all transitions to KVM_MP_STATE

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Message-ID: <20250113200150.487409-3-jmattson@google.com>
Date: Mon, 13 Jan 2025 12:01:44 -0800
From: Jim Mattson <jmattson@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H . Peter Anvin" <hpa@...or.com>, David Woodhouse <dwmw2@...radead.org>, Paul Durrant <paul@....org>, 
	Gleb Natapov <gleb@...hat.com>, Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>, 
	Suzuki Poulose <suzuki@...ibm.com>, Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>, 
	Jan Kiszka <jan.kiszka@...mens.com>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Jim Mattson <jmattson@...gle.com>
Subject: [PATCH 2/2] KVM: x86: Clear pv_unhalted on all transitions to KVM_MP_STATE_RUNNABLE

In kvm_set_mp_state(), ensure that vcpu->arch.pv.pv_unhalted is always
cleared on a transition to KVM_MP_STATE_RUNNABLE, so that the next HLT
instruction will be respected.

The "fixes" list may be incompplete.

Fixes: 6aef266c6e17 ("kvm hypervisor : Add a hypercall to KVM hypervisor to support pv-ticketlocks")
Fixes: b6b8a1451fc4 ("KVM: nVMX: Rework interception of IRQs and NMIs")
Fixes: 38c0b192bd6d ("KVM: SVM: leave halted state on vmexit")
Signed-off-by: Jim Mattson <jmattson@...gle.com>
---
 arch/x86/kvm/svm/sev.c | 1 -
 arch/x86/kvm/x86.c     | 1 -
 arch/x86/kvm/x86.h     | 2 ++
 3 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index b4d9efd7537d..73e15e7658c2 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3869,7 +3869,6 @@ static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)
 		svm->vmcb->control.vmsa_pa = pfn_to_hpa(pfn);
 
 		/* Mark the vCPU as runnable */
-		vcpu->arch.pv.pv_unhalted = false;
 		kvm_set_mp_state(vcpu, KVM_MP_STATE_RUNNABLE);
 
 		svm->sev_es.snp_vmsa_gpa = INVALID_PAGE;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d6679df95a75..4b21ed6803c6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11207,7 +11207,6 @@ static inline int vcpu_block(struct kvm_vcpu *vcpu)
 	switch(vcpu->arch.mp_state) {
 	case KVM_MP_STATE_HALTED:
 	case KVM_MP_STATE_AP_RESET_HOLD:
-		vcpu->arch.pv.pv_unhalted = false;
 		kvm_set_mp_state(vcpu, KVM_MP_STATE_RUNNABLE);
 		fallthrough;
 	case KVM_MP_STATE_RUNNABLE:
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index bc3b5a9490c6..cc06631027bd 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -124,6 +124,8 @@ static inline bool kvm_vcpu_has_run(struct kvm_vcpu *vcpu)
 static inline void kvm_set_mp_state(struct kvm_vcpu *vcpu, int mp_state)
 {
 	vcpu->arch.mp_state = mp_state;
+	if (mp_state == KVM_MP_STATE_RUNNABLE)
+		vcpu->arch.pv.pv_unhalted = false;
 }
 
 static inline bool kvm_is_exception_pending(struct kvm_vcpu *vcpu)
-- 
2.47.1.688.g23fc6f90ad-goog