Il 10/03/2014 09:48, Liu, Jinsong ha scritto:
From 5854070994c5002b3a37577165ed3e82f36f712d Mon Sep 17 00:00:00 2001
From: Liu Jinsong <jinsong.liu@xxxxxxxxx>
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 <jinsong.liu@xxxxxxxxx>
---
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) &&
Too many parentheses in this "if".
+ (kvm_x86_ops->mpx_supported ?
+ !kvm_x86_ops->mpx_supported() : 1))
Better: "!kvm_x86_ops->mpx_supported || !kvm_x86_ops->mpx_supported()"
but I'm leaning towards adding an implementation of mpx_supported to SVM
too (it will always return false).
+ 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);
Thanks Liu. Indeed I could not reproduce Robert's issue, though it
might be possible to get it with nested virtualization. I'll send a
similar patch that I was testing.
Paolo
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