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kvm: vmx: Don't set hardware IA32_CSTAR MSR on VM-entry 

SYSCALL raises #UD in compatibility mode on Intel CPUs, so it's
pointless to load the guest's IA32_CSTAR value into the hardware MSR.

IA32_CSTAR still provides 48 bits of storage on Intel CPUs that have
CPUID.80000001:EDX.LM[bit 29] set, so we cannot remove it from the
vmx_msr_index[] array.

Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Jim Mattson 2018-12-05 15:29:00 -08:00 committed by Paolo Bonzini
parent 898a811f14
commit db31c8f5af
1 changed files with 0 additions and 3 deletions
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3
arch/x86/kvm/vmx/vmx.c
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@ -1380,9 +1380,6 @@ static void setup_msrs(struct vcpu_vmx *vmx)
if (index >= 0)
move_msr_up(vmx, index, save_nmsrs++);
index = __find_msr_index(vmx, MSR_LSTAR);
if (index >= 0)
move_msr_up(vmx, index, save_nmsrs++);
index = __find_msr_index(vmx, MSR_CSTAR);
if (index >= 0)
move_msr_up(vmx, index, save_nmsrs++);
/*