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From: Sean Christopherson <seanjc@google.com>
To: Madhavan Srinivasan <maddy@linux.ibm.com>,
	Sean Christopherson <seanjc@google.com>,
	 Paolo Bonzini <pbonzini@redhat.com>
Cc: Nicholas Piggin <npiggin@gmail.com>,
	linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org,
	 linux-kernel@vger.kernel.org, Jim Mattson <jmattson@google.com>,
	 James Houghton <jthoughton@google.com>,
	Chris Mason <mason@kernel.org>
Subject: [PATCH v3 12/15] KVM: nVMX: Cancel the nested VMX Preemption Timer's hrtimer in free_nested()
Date: Tue, 27 Oct 2026 15:12:05 -0700	[thread overview]
Message-ID: <20261027221209.1560865-13-seanjc@google.com> (raw)
In-Reply-To: <20261027221209.1560865-1-seanjc@google.com>

Cancel the hrtimer used to emulate a VMX Preemption Timer for L2 when
freeing nested state instead of precisely canceling the timer if and only
if the vCPU is/was in L2.  hrtimer_cancel() bails early if the timer isn't
running, and KVM initializes the timer when allocating nested state, i.e.
canceling the timer even if it's not fully in-use is glorified nop.

Canceling the timer even if L1 is active will allow KVM to leave the vCPU
in L2 without having to retain an "is_guest_mode()" check just to cancel
timer.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/vmx/nested.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 1b30ad7731ee..553915015a75 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -339,6 +339,8 @@ static void free_nested(struct kvm_vcpu *vcpu)
 
 	kvm_clear_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu);
 
+	hrtimer_cancel(&vmx->nested.preemption_timer);
+
 	vmx->nested.vmxon = false;
 	vmx->nested.smm.vmxon = false;
 	vmx->nested.vmxon_ptr = INVALID_GPA;
@@ -401,7 +403,6 @@ void nested_vmx_free_vcpu(struct kvm_vcpu *vcpu)
 
 	vcpu_load(vcpu);
 	if (is_guest_mode(vcpu)) {
-		hrtimer_cancel(&vmx->nested.preemption_timer);
 		leave_guest_mode(vcpu);
 		vmx_switch_vmcs(vcpu, &vmx->vmcs01);
 	}
-- 
2.56.0.307.g5fe7bd680c-goog



  parent reply	other threads:[~2026-10-27 22:13 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-27 22:11 [PATCH v3 00/15] KVM: Fix+harden against bad uaccess using dying VM Sean Christopherson
2026-10-27 22:11 ` [PATCH v3 01/15] KVM: Reject user accesses to guest memory if current->mm != kvm->mm Sean Christopherson
2026-10-27 22:11 ` [PATCH v3 02/15] KVM: nVMX: Don't force a full nested VM-Exit when destroying a vCPU Sean Christopherson
2026-10-27 22:54   ` Sean Christopherson
2026-10-27 22:11 ` [PATCH v3 03/15] KVM: PPC: Flush/zap all memslots on kvm_arch_flush_shadow_all() Sean Christopherson
2026-10-27 22:11 ` [PATCH v3 04/15] KVM: x86: Unmap VMAs for KVM-internal memslots when the memslot is freed Sean Christopherson
2026-10-27 22:27   ` sashiko-bot
2026-10-27 22:11 ` [PATCH v3 05/15] KVM: Disallow setting memslots when the VM is being destroyed Sean Christopherson
2026-10-27 22:11 ` [PATCH v3 06/15] KVM: Destroy memslots immediately after mmu_notifiers are unregistered Sean Christopherson
2026-10-27 22:12 ` [PATCH v3 07/15] KVM: WARN if KVM attempts to do guest-related uaccess with "wrong" process Sean Christopherson
2026-10-27 22:12 ` [PATCH v3 08/15] KVM: WARN and reject guest-based uaccess if VM is dying Sean Christopherson
2026-10-28  0:26   ` James Houghton
2026-10-27 22:12 ` [PATCH v3 09/15] KVM: Pre-check uaccesses in KVM's APIs to read/write guest memory Sean Christopherson
2026-10-28  0:22   ` James Houghton
2026-10-27 22:12 ` [PATCH v3 10/15] KVM: VMX: Explicility free vmcs01, not the current VMCS, in vCPU free paths Sean Christopherson
2026-10-28  0:33   ` James Houghton
2026-10-27 22:12 ` [PATCH v3 11/15] KVM: nVMX: Don't explicitly VMCLEAR+free() vmcs01's shadow VMCS when freeing vCPU Sean Christopherson
2026-10-27 22:12 ` Sean Christopherson [this message]
2026-10-27 22:12 ` [PATCH v3 13/15] KVM: VMX: Explicitly remove dying vCPUs from the PI wakeup list Sean Christopherson
2026-10-27 22:32   ` sashiko-bot
2026-10-27 22:12 ` [PATCH v3 14/15] KVM: nVMX: Don't switch to vmcs01 when freeing a vCPU Sean Christopherson
2026-10-27 22:12 ` [PATCH v3 15/15] KVM: nVMX: Don't load+put the vCPU when freeing nested state for a dying vCPU Sean Christopherson
2026-10-28  9:18 ` [syzbot ci] Re: KVM: Fix+harden against bad uaccess using dying VM syzbot ci

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