[prev in list] [next in list] [prev in thread] [next in thread]
List: kvm-commits
Subject: [COMMIT master] KVM: VMX: Fix host userspace gsbase corruption
From: Avi Kivity <avi () redhat ! com>
Date: 2010-11-23 12:54:46
Message-ID: 20101123125446.898EF250AE7 () cleopatra ! tlv ! redhat ! com
[Download RAW message or body]
From: Avi Kivity <avi@redhat.com>
We now use load_gs_index() to load gs safely; unfortunately this also
changes MSR_KERNEL_GS_BASE, which we managed separately. This resulted
in confusion and breakage running 32-bit host userspace on a 64-bit kernel.
Fix by
- saving guest MSR_KERNEL_GS_BASE before we we reload the host's gs
- doing the host save/load unconditionally, instead of only when in guest
long mode
Things can be cleaned up further, but this is the minmal fix for now.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 9367abc..0badeac 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -821,10 +821,9 @@ static void vmx_save_host_state(struct kvm_vcpu *vcpu)
#endif
#ifdef CONFIG_X86_64
- if (is_long_mode(&vmx->vcpu)) {
- rdmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base);
+ rdmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base);
+ if (is_long_mode(&vmx->vcpu))
wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);
- }
#endif
for (i = 0; i < vmx->save_nmsrs; ++i)
kvm_set_shared_msr(vmx->guest_msrs[i].index,
@@ -839,11 +838,14 @@ static void __vmx_load_host_state(struct vcpu_vmx *vmx)
++vmx->vcpu.stat.host_state_reload;
vmx->host_state.loaded = 0;
+#ifdef CONFIG_X86_64
+ if (is_long_mode(&vmx->vcpu))
+ rdmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);
+#endif
if (vmx->host_state.gs_ldt_reload_needed) {
kvm_load_ldt(vmx->host_state.ldt_sel);
#ifdef CONFIG_X86_64
load_gs_index(vmx->host_state.gs_sel);
- wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gs);
#else
loadsegment(gs, vmx->host_state.gs_sel);
#endif
@@ -852,10 +854,7 @@ static void __vmx_load_host_state(struct vcpu_vmx *vmx)
loadsegment(fs, vmx->host_state.fs_sel);
reload_tss();
#ifdef CONFIG_X86_64
- if (is_long_mode(&vmx->vcpu)) {
- rdmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);
- wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base);
- }
+ wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base);
#endif
if (current_thread_info()->status & TS_USEDFPU)
clts();
--
To unsubscribe from this list: send the line "unsubscribe kvm-commits" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
[prev in list] [next in list] [prev in thread] [next in thread]
Configure |
About |
News |
Add a list |
Sponsored by KoreLogic