linux-kernel - [PATCH v2 43/50] KVM: Ensure CPU is stable during low level hardware enable/disable

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Date:   Wed, 30 Nov 2022 23:09:27 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, Marc Zyngier <maz@...nel.org>,
        Huacai Chen <chenhuacai@...nel.org>,
        Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
        Anup Patel <anup@...infault.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Matthew Rosato <mjrosato@...ux.ibm.com>,
        Eric Farman <farman@...ux.ibm.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Paul Durrant <paul@....org>
Cc:     James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Atish Patra <atishp@...shpatra.org>,
        David Hildenbrand <david@...hat.com>, kvm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        kvmarm@...ts.cs.columbia.edu, linux-mips@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, kvm-riscv@...ts.infradead.org,
        linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, Yuan Yao <yuan.yao@...el.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Isaku Yamahata <isaku.yamahata@...el.com>,
        "Philippe Mathieu-Daudé" <philmd@...aro.org>,
        Fabiano Rosas <farosas@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Kai Huang <kai.huang@...el.com>, Chao Gao <chao.gao@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH v2 43/50] KVM: Ensure CPU is stable during low level hardware enable/disable

Use the non-raw smp_processor_id() in the low hardware enable/disable
helpers as KVM absolutely relies on the CPU being stable, e.g. KVM would
end up with incorrect state if the task were migrated between accessing
cpus_hardware_enabled and actually enabling/disabling hardware.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 virt/kvm/kvm_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d985b24c423b..a46d61e9c053 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5028,7 +5028,7 @@ static struct miscdevice kvm_dev = {
 
 static void hardware_enable_nolock(void *junk)
 {
-	int cpu = raw_smp_processor_id();
+	int cpu = smp_processor_id();
 	int r;
 
 	if (cpumask_test_cpu(cpu, cpus_hardware_enabled))
@@ -5070,7 +5070,7 @@ static int kvm_online_cpu(unsigned int cpu)
 
 static void hardware_disable_nolock(void *junk)
 {
-	int cpu = raw_smp_processor_id();
+	int cpu = smp_processor_id();
 
 	if (!cpumask_test_cpu(cpu, cpus_hardware_enabled))
 		return;
-- 
2.38.1.584.g0f3c55d4c2-goog