[PATCH 5/6] KVM: x86: Remove WARN_ON in kvm_arch_check_processor_compat

From: Chao Gao <chao.gao@intel.com>
To: kvm@vger.kernel.org, pbonzini@redhat.com, kevin.tian@intel.com,
	tglx@linutronix.de
Cc: Chao Gao <chao.gao@intel.com>,
	Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH 5/6] KVM: x86: Remove WARN_ON in kvm_arch_check_processor_compat
Date: Mon, 27 Dec 2021 16:15:11 +0800	[thread overview]
Message-ID: <20211227081515.2088920-6-chao.gao@intel.com> (raw)
In-Reply-To: <20211227081515.2088920-1-chao.gao@intel.com>

kvm_arch_check_processor_compat() needn't be called with interrupt
disabled, as it only reads some CRs/MSRs which won't be clobbered
by interrupt handlers or softirq.

What really needed is disabling preemption. No additional check is
added because if CONFIG_DEBUG_PREEMPT is enabled, smp_processor_id()
(right above the WARN_ON()) can help to detect any violation.

Signed-off-by: Chao Gao <chao.gao@intel.com>
---
 arch/x86/kvm/x86.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index aa09c8792134..a80e3b0c11a8 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11384,8 +11384,6 @@ int kvm_arch_check_processor_compat(void)
 {
 	struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
 
-	WARN_ON(!irqs_disabled());
-
 	if (__cr4_reserved_bits(cpu_has, c) !=
 	    __cr4_reserved_bits(cpu_has, &boot_cpu_data))
 		return -EIO;
-- 
2.25.1

