linux-kernel - [PATCH 6/9] KVM: VMX: Use the kernel's version of VMXOFF

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Date:   Wed, 30 Dec 2020 16:26:59 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        "H. Peter Anvin" <hpa@...or.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "David P . Reed" <dpreed@...pplum.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Uros Bizjak <ubizjak@...il.com>
Subject: [PATCH 6/9] KVM: VMX: Use the kernel's version of VMXOFF

Drop kvm_cpu_vmxoff() in favor of the kernel's cpu_vmxoff().  Modify the
latter to return -EIO on fault so that KVM can invoke
kvm_spurious_fault() when appropriate.  In addition to the obvious code
reuse, dropping kvm_cpu_vmxoff() also eliminates VMX's last usage of the
__ex()/__kvm_handle_fault_on_reboot() macros, thus helping pave the way
toward dropping them entirely.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/include/asm/virtext.h |  7 ++++++-
 arch/x86/kvm/vmx/vmx.c         | 15 +++------------
 2 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/virtext.h b/arch/x86/include/asm/virtext.h
index 2cc585467667..8757078d4442 100644
--- a/arch/x86/include/asm/virtext.h
+++ b/arch/x86/include/asm/virtext.h
@@ -41,13 +41,18 @@ static inline int cpu_has_vmx(void)
  * faults are guaranteed to be due to the !post-VMXON check unless the CPU is
  * magically in RM, VM86, compat mode, or at CPL>0.
  */
-static inline void cpu_vmxoff(void)
+static inline int cpu_vmxoff(void)
 {
 	asm_volatile_goto("1: vmxoff\n\t"
 			  _ASM_EXTABLE(1b, %l[fault])
 			  ::: "cc", "memory" : fault);
+
+	cr4_clear_bits(X86_CR4_VMXE);
+	return 0;
+
 fault:
 	cr4_clear_bits(X86_CR4_VMXE);
+	return -EIO;
 }
 
 static inline int cpu_vmx_enabled(void)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 131f390ade24..1a3b508ba8c1 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2321,21 +2321,12 @@ static void vmclear_local_loaded_vmcss(void)
 		__loaded_vmcs_clear(v);
 }
 
-
-/* Just like cpu_vmxoff(), but with the __kvm_handle_fault_on_reboot()
- * tricks.
- */
-static void kvm_cpu_vmxoff(void)
-{
-	asm volatile (__ex("vmxoff"));
-
-	cr4_clear_bits(X86_CR4_VMXE);
-}
-
 static void hardware_disable(void)
 {
 	vmclear_local_loaded_vmcss();
-	kvm_cpu_vmxoff();
+
+	if (cpu_vmxoff())
+		kvm_spurious_fault();
 
 	intel_pt_handle_vmx(0);
 }
-- 
2.29.2.729.g45daf8777d-goog