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[Qemu-devel] [PATCH] KVM: x86: Work around buggy MPX platform


From: Liu, Jinsong
Subject: [Qemu-devel] [PATCH] KVM: x86: Work around buggy MPX platform
Date: Mon, 10 Mar 2014 08:48:15 +0000

>From 5854070994c5002b3a37577165ed3e82f36f712d Mon Sep 17 00:00:00 2001
From: Liu Jinsong <address@hidden>
Date: Sat, 8 Mar 2014 04:40:02 +0800
Subject: [PATCH] KVM: x86: Work around buggy MPX platform

Work around buggy MPX platform which support MSR_IA32_BNDCFGS
but has issue at, say, VMX ucode.

Signed-off-by: Liu Jinsong <address@hidden>
---
 arch/x86/kvm/x86.c |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1e91a24..1fc184d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3936,6 +3936,16 @@ static void kvm_init_msr_list(void)
        for (i = j = KVM_SAVE_MSRS_BEGIN; i < ARRAY_SIZE(msrs_to_save); i++) {
                if (rdmsr_safe(msrs_to_save[i], &dummy[0], &dummy[1]) < 0)
                        continue;
+
+               /*
+                * Work around some buggy MPX platform which support
+                * MSR_IA32_BNDCFGS but has issue at, say, VMX ucode.
+                */
+               if ((msrs_to_save[i] == MSR_IA32_BNDCFGS) &&
+                       (kvm_x86_ops->mpx_supported   ?
+                       !kvm_x86_ops->mpx_supported() : 1))
+                               continue;
+
                if (j < i)
                        msrs_to_save[j] = msrs_to_save[i];
                j++;
@@ -5576,9 +5586,11 @@ int kvm_arch_init(void *opaque)
                goto out_free_percpu;
 
        kvm_set_mmio_spte_mask();
-       kvm_init_msr_list();
 
        kvm_x86_ops = ops;
+
+       kvm_init_msr_list();
+
        kvm_mmu_set_mask_ptes(PT_USER_MASK, PT_ACCESSED_MASK,
                        PT_DIRTY_MASK, PT64_NX_MASK, 0);
 
-- 
1.7.1



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