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From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	 David Woodhouse <dwmw2@infradead.org>,
	Paul Durrant <paul@xen.org>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	 syzbot+352e553a86e0d75f5120@syzkaller.appspotmail.com,
	 Paul Durrant <pdurrant@amazon.com>,
	David Woodhouse <dwmw@amazon.co.uk>,
	 Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: [PATCH v2 02/11] KVM: x86: Eliminate "handling" of impossible errors during SUSPEND
Date: Fri, 31 Jan 2025 17:38:18 -0800	[thread overview]
Message-ID: <20250201013827.680235-3-seanjc@google.com> (raw)
In-Reply-To: <20250201013827.680235-1-seanjc@google.com>

Drop KVM's handling of kvm_set_guest_paused() failure when reacting to a
SUSPEND notification, as kvm_set_guest_paused() only "fails" if the vCPU
isn't using kvmclock, and KVM's notifier callback pre-checks that kvmclock
is active.  I.e. barring some bizarre edge case that shouldn't be treated
as an error in the first place, kvm_arch_suspend_notifier() can't fail.

Reviewed-by: Paul Durrant <paul@xen.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/x86.c | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 26e18c9b0375..ef21158ec6b2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6905,21 +6905,15 @@ static int kvm_arch_suspend_notifier(struct kvm *kvm)
 {
 	struct kvm_vcpu *vcpu;
 	unsigned long i;
-	int ret = 0;
 
-	kvm_for_each_vcpu(i, vcpu, kvm) {
-		if (!vcpu->arch.pv_time.active)
-			continue;
+	/*
+	 * Ignore the return, marking the guest paused only "fails" if the vCPU
+	 * isn't using kvmclock; continuing on is correct and desirable.
+	 */
+	kvm_for_each_vcpu(i, vcpu, kvm)
+		(void)kvm_set_guest_paused(vcpu);
 
-		ret = kvm_set_guest_paused(vcpu);
-		if (ret) {
-			kvm_err("Failed to pause guest VCPU%d: %d\n",
-				vcpu->vcpu_id, ret);
-			break;
-		}
-	}
-
-	return ret ? NOTIFY_BAD : NOTIFY_DONE;
+	return NOTIFY_DONE;
 }
 
 int kvm_arch_pm_notifier(struct kvm *kvm, unsigned long state)
-- 
2.48.1.362.g079036d154-goog


  parent reply	other threads:[~2025-02-01  1:38 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-02-01  1:38 [PATCH v2 00/11] KVM: x86: pvclock fixes and cleanups Sean Christopherson
2025-02-01  1:38 ` [PATCH v2 01/11] KVM: x86: Don't take kvm->lock when iterating over vCPUs in suspend notifier Sean Christopherson
2025-02-01  1:38 ` Sean Christopherson [this message]
2025-02-01  1:38 ` [PATCH v2 03/11] KVM: x86: Drop local pvclock_flags variable in kvm_guest_time_update() Sean Christopherson
2025-02-01  1:38 ` [PATCH v2 04/11] KVM: x86: Process "guest stopped request" once per guest time update Sean Christopherson
2025-02-04  9:19   ` Paul Durrant
2025-02-01  1:38 ` [PATCH v2 05/11] KVM: x86/xen: Use guest's copy of pvclock when starting timer Sean Christopherson
2025-02-04  9:26   ` Paul Durrant
2025-02-01  1:38 ` [PATCH v2 06/11] KVM: x86: Don't bleed PVCLOCK_GUEST_STOPPED across PV clocks Sean Christopherson
2025-02-04  9:28   ` Paul Durrant
2025-02-01  1:38 ` [PATCH v2 07/11] KVM: x86: Set PVCLOCK_GUEST_STOPPED only for kvmclock, not for Xen PV clock Sean Christopherson
2025-02-04  9:31   ` Paul Durrant
2025-02-01  1:38 ` [PATCH v2 08/11] KVM: x86: Pass reference pvclock as a param to kvm_setup_guest_pvclock() Sean Christopherson
2025-02-04  9:33   ` Paul Durrant
2025-02-04  9:38     ` Paul Durrant
2025-02-04 19:23       ` Sean Christopherson
2025-02-01  1:38 ` [PATCH v2 09/11] KVM: x86: Remove per-vCPU "cache" of its reference pvclock Sean Christopherson
2025-02-01  1:38 ` [PATCH v2 10/11] KVM: x86: Setup Hyper-V TSC page before Xen PV clocks (during clock update) Sean Christopherson
2025-02-01  1:38 ` [PATCH v2 11/11] KVM: x86: Override TSC_STABLE flag for Xen PV clocks in kvm_guest_time_update() Sean Christopherson
2025-02-15  0:50 ` [PATCH v2 00/11] KVM: x86: pvclock fixes and cleanups Sean Christopherson

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