linux-kernel - [PATCH] kvm/svm: Setup MCG

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Date:   Sun, 26 Mar 2017 23:51:24 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     KVM <kvm@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Subject: [PATCH] kvm/svm: Setup MCG_CAP on AMD properly

From: Borislav Petkov <bp@...e.de>

MCG_CAP[63:9] bits are reserved on AMD. However, on an AMD guest, this
MSR returns 0x100010a. More specifically, bit 24 is set, which is simply
wrong. That bit is MCG_SER_P and is present only on Intel. Thus, clean
up the reserved bits in order not to confuse guests.

Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Joerg Roedel <joro@...tes.org>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: "Radim Krčmář" <rkrcmar@...hat.com>
---
 arch/x86/kvm/svm.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index c02b9af2056a..aba6100ebb8d 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5251,6 +5251,12 @@ static inline void avic_post_state_restore(struct kvm_vcpu *vcpu)
 	avic_handle_ldr_update(vcpu);
 }
 
+static void svm_setup_mce(struct kvm_vcpu *vcpu)
+{
+	/* [63:9] are reserved. */
+	vcpu->arch.mcg_cap &= 0x1ff;
+}
+
 static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
 	.cpu_has_kvm_support = has_svm,
 	.disabled_by_bios = is_disabled,
@@ -5362,6 +5368,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
 	.pmu_ops = &amd_pmu_ops,
 	.deliver_posted_interrupt = svm_deliver_avic_intr,
 	.update_pi_irte = svm_update_pi_irte,
+	.setup_mce = svm_setup_mce,
 };
 
 static int __init svm_init(void)
-- 
2.11.0