linux-kernel - [PATCH v2 4/6] X86/nVMX: Properly set spec_ctrl and pred

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Date:   Sat, 10 Feb 2018 23:39:25 +0000
From:   David Woodhouse <dwmw@...zon.co.uk>
To:     tglx@...utronix.de, karahmed@...zon.de, sironi@...zon.de,
        x86@...nel.org, kvm@...r.kernel.org, torvalds@...ux-foundation.org,
        pbonzini@...hat.com, linux-kernel@...r.kernel.org, bp@...en8.de,
        peterz@...radead.org, jmattson@...gle.com, rkrcmar@...hat.com,
        arjan.van.de.ven@...el.com, dave.hansen@...el.com
Subject: [PATCH v2 4/6] X86/nVMX: Properly set spec_ctrl and pred_cmd before merging MSRs

From: KarimAllah Ahmed <karahmed@...zon.de>

These two variables should check whether SPEC_CTRL and PRED_CMD are
supposed to be passed through to L2 guests or not. While
msr_write_intercepted_l01 would return 'true' if it is not passed through.

So just invert the result of msr_write_intercepted_l01 to implement the
correct semantics.

Fixes: 086e7d4118cc ("KVM: VMX: Allow direct access to MSR_IA32_SPEC_CTRL")
Signed-off-by: KarimAllah Ahmed <karahmed@...zon.de>
Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
Reviewed-by: Jim Mattson <jmattson@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Cc: kvm@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
---
 arch/x86/kvm/vmx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index bee4c49..599179b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10219,8 +10219,8 @@ static inline bool nested_vmx_merge_msr_bitmap(struct kvm_vcpu *vcpu,
 	 *    updated to reflect this when L1 (or its L2s) actually write to
 	 *    the MSR.
 	 */
-	bool pred_cmd = msr_write_intercepted_l01(vcpu, MSR_IA32_PRED_CMD);
-	bool spec_ctrl = msr_write_intercepted_l01(vcpu, MSR_IA32_SPEC_CTRL);
+	bool pred_cmd = !msr_write_intercepted_l01(vcpu, MSR_IA32_PRED_CMD);
+	bool spec_ctrl = !msr_write_intercepted_l01(vcpu, MSR_IA32_SPEC_CTRL);
 
 	if (!nested_cpu_has_virt_x2apic_mode(vmcs12) &&
 	    !pred_cmd && !spec_ctrl)
-- 
2.7.4