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([124.93.80.37]) by smtp.googlemail.com with ESMTPSA id 41be03b00d2f7-ba900fa571esm10913877a12.26.2025.11.09.19.32.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 09 Nov 2025 19:33:01 -0800 (PST) From: Wanpeng Li To: Peter Zijlstra , Ingo Molnar , Thomas Gleixner , Paolo Bonzini , Sean Christopherson Cc: Steven Rostedt , Vincent Guittot , Juri Lelli , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Wanpeng Li Subject: [PATCH 06/10] KVM: Fix last_boosted_vcpu index assignment bug Date: Mon, 10 Nov 2025 11:32:27 +0800 Message-ID: <20251110033232.12538-7-kernellwp@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251110033232.12538-1-kernellwp@gmail.com> References: <20251110033232.12538-1-kernellwp@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Wanpeng Li From: Wanpeng Li In kvm_vcpu_on_spin(), the loop counter 'i' is incorrectly written to last_boosted_vcpu instead of the actual vCPU index 'idx'. This causes last_boosted_vcpu to store the loop iteration count rather than the vCPU index, leading to incorrect round-robin behavior in subsequent directed yield operations. Fix this by using 'idx' instead of 'i' in the assignment. Signed-off-by: Wanpeng Li --- virt/kvm/kvm_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index b7a0ae2a7b20..cde1eddbaa91 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4026,7 +4026,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me, bool yield_to_kernel_mode) yielded = kvm_vcpu_yield_to(vcpu); if (yielded > 0) { - WRITE_ONCE(kvm->last_boosted_vcpu, i); + WRITE_ONCE(kvm->last_boosted_vcpu, idx); break; } else if (yielded < 0 && !--try) { break; -- 2.43.0