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[PATCH v2] x86/msr: don't inject #GP when trying to read FEATURE_CONTROL
- To: <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Roger Pau Monne <roger.pau@xxxxxxxxxx>
- Date: Tue, 29 Dec 2020 17:58:01 +0100
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- Cc: Roger Pau Monne <roger.pau@xxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>
- Delivery-date: Tue, 29 Dec 2020 16:58:24 +0000
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- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
Windows 10 will triple fault if #GP is injected when attempting to
read the FEATURE_CONTROL MSR on Intel or compatible hardware. Fix this
by injecting a #GP only when the vendor doesn't support the MSR, even
if there are no features to expose.
Fixes: 39ab598c50a2 ('x86/pv: allow reading FEATURE_CONTROL MSR')
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Changes since v1:
- Allow Shanghai CPUs to access FEATURE_CONTROL without #GP.
---
xen/arch/x86/msr.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/xen/arch/x86/msr.c b/xen/arch/x86/msr.c
index be8e363862..6dfd3d5f97 100644
--- a/xen/arch/x86/msr.c
+++ b/xen/arch/x86/msr.c
@@ -176,7 +176,8 @@ int guest_rdmsr(struct vcpu *v, uint32_t msr, uint64_t *val)
switch ( msr )
{
case MSR_IA32_FEATURE_CONTROL:
- if ( !cp->basic.vmx && !vmce_has_lmce(v) )
+ if ( !(cp->x86_vendor & (X86_VENDOR_INTEL | X86_VENDOR_CENTAUR |
+ X86_VENDOR_SHANGHAI)) )
goto gp_fault;
*val = IA32_FEATURE_CONTROL_LOCK;
--
2.29.2
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