From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794419388; b=jipiOI62eWx57EliSA7uAwzjD5uTrJ9361GlzTPl5yDpYrHvd19r0+O6QhCiNG/XRndZ hkSnkQrhnY/wWsnvgcQJaVLCpDZdNOoYr8nMMI+1F7woy8wgY0q9KMpU/htbeUUx10a4p t+cAHHVoUAJt/67rgnq6b6far2dylDatJOIMYyBpbQdDmG2vPHdtOpsFVnK37lCGBmmqq RTlCq8HzZgkHqa4X3dDhiqG20cewid+iyRopY+oLYF59hqqGoEmy20n/LYEbSg7hCuZtE u0k/6JvzwMjtGbj9c0hvWrtV1Noh7PIF8wEh21lcKAmq+TEDvJiNHZPlv/gQ8cswcKg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794419388; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=urTcQ13koFRYQxvx3+1awm06YxW2thycTA5i5g41OAM=; b=h1NEyJFjtThZ2GBKhgADVbUdGI4ISMlVhVIi3cY9As6O6j3xdSzV0T5qZvlX19AE73DI 2jx7QerAnNm+m4IXkkKdja/w3QXoN4FZlGnAFarJJsP+MbwTqg4fAPrEUpzBZ8CbiMXHM 8+UyHDiXVlaLny5t5cZ32AUqdvFVBCTKmq/+4E/OSAhzkNgN9hOZQ/WNFJorky1nlaCDL hv0/5jgdHtouaxgZ97MH+MV61FLsKyWljieB48CHgOFsgT1lq4j8tufvf5H5xCXGXOj0X 4vAFM+asdWvzkx2iZ2UHa2JMtfeGUSn8kQakLgkcTzBm8UfxZ1uvcq3coqdweXRjVTg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=AvykjvDP; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CB10A606A31C for ; Wed, 11 Nov 2026 17:49:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=AvykjvDP Received: by smtp.kernel.org (Postfix) with ESMTPSA id F03261F00A05; Wed, 11 Nov 2026 17:49:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794419388; bh=urTcQ13koFRYQxvx3+1awm06YxW2thycTA5i5g41OAM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=AvykjvDP7khYfxNnSgRD2M62/HYDnU4Hi4ZTzETG7W1HzkmssxSEzHVB4OxAsTrKH 1TACf7S0jX7Za2Gh/NBmv8APIbwzhUBmr4SfFRodqZAtAseVVWDSEM5csEZcdP9U47 /KQJes7otJtOuAi8ZW4fmf00QvruPyZkFarGawSA4HwN0rLUsevn8unZEjWuhwlGxR 2cAHI4JsDsMdLBUEhQ3cj6EQ/FEvG2Vs6D7tym85gNY0vM09/R79knjXgUci2XUiWF fOeEP5XAiew3v6+nzArPNhdewz7OcNlrlQn//xaOSvXAS6DkjGSTkNLfeN9Xpaigf8 WbJfLhQGseLXQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Marc Zyngier , Fuad Tabba , Sasha Levin Subject: [PATCH 5.10.y] KVM: arm64: Turn vcpu->arch.pause into a counter Date: Wed, 11 Nov 2026 12:49:46 -0500 Message-ID: <20261111174927.3663842-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107062353-failed-5.10-e64309198eda@kernel.org> References: <20261107062353-failed-5.10-e64309198eda@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Marc Zyngier [ Upstream commit e64309198eda29415a95113def92aa40196cd422 ] We have situations where we can call kvm_arm_halt_guest() without holding config_lock, which means that halt and resume can overlap in funny ways when called from separate contexts, and result in situations where a vcpu is resumed while other parts of KVM assume it is halted. Consequences are left to the imagination of the reader. Fix this sorry situation by turning kvm_vcpu_arch::pause into an atomic counter, which makes the races described above harmless. Fixes: 3b92830ad41b2 ("KVM: arm/arm64: implement kvm_arm_[halt,resume]_guest") Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20261015100539.1011760-5-maz@kernel.org Signed-off-by: Marc Zyngier [ sashal: adapted pause handling to existing power_off checks and vcpu_req_sleep(), retaining direct rcuwait_wake_up() calls ] Signed-off-by: Sasha Levin --- arch/arm64/include/asm/kvm_host.h | 2 +- arch/arm64/kvm/arm.c | 13 +++++++------ 2 files changed, 8 insertions(+), 7 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 48ee1fe3aca40..16062b15131cf 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -354,7 +354,7 @@ struct kvm_vcpu_arch { bool power_off; /* Don't run the guest (internal implementation need) */ - bool pause; + atomic_t pause; /* Cache some mmu pages needed inside spinlock regions */ struct kvm_mmu_memory_cache mmu_page_cache; diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 528229636c635..198141e2ecfc8 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -289,6 +289,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) kvm_arm_pvtime_vcpu_init(&vcpu->arch); vcpu->arch.hw_mmu = &vcpu->kvm->arch.mmu; + atomic_set(&vcpu->arch.pause, 0); err = kvm_vgic_vcpu_init(vcpu); if (err) @@ -447,7 +448,7 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *v) { bool irq_lines = *vcpu_hcr(v) & (HCR_VI | HCR_VF); return ((irq_lines || kvm_vgic_vcpu_pending_irq(v)) - && !v->arch.power_off && !v->arch.pause); + && !v->arch.power_off && !atomic_read(&v->arch.pause)); } bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu) @@ -589,7 +590,7 @@ void kvm_arm_halt_guest(struct kvm *kvm) struct kvm_vcpu *vcpu; kvm_for_each_vcpu(i, vcpu, kvm) - vcpu->arch.pause = true; + atomic_inc(&vcpu->arch.pause); kvm_make_all_cpus_request(kvm, KVM_REQ_SLEEP); } @@ -599,8 +600,8 @@ void kvm_arm_resume_guest(struct kvm *kvm) struct kvm_vcpu *vcpu; kvm_for_each_vcpu(i, vcpu, kvm) { - vcpu->arch.pause = false; - rcuwait_wake_up(kvm_arch_vcpu_get_wait(vcpu)); + if (atomic_dec_and_test(&vcpu->arch.pause)) + rcuwait_wake_up(kvm_arch_vcpu_get_wait(vcpu)); } } @@ -609,10 +610,10 @@ static void vcpu_req_sleep(struct kvm_vcpu *vcpu) struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu); rcuwait_wait_event(wait, - (!vcpu->arch.power_off) &&(!vcpu->arch.pause), + !vcpu->arch.power_off && !atomic_read(&vcpu->arch.pause), TASK_INTERRUPTIBLE); - if (vcpu->arch.power_off || vcpu->arch.pause) { + if (vcpu->arch.power_off || atomic_read(&vcpu->arch.pause)) { /* Awaken to handle a signal, request we sleep again later. */ kvm_make_request(KVM_REQ_SLEEP, vcpu); } -- 2.53.0