| Message ID | 1479121286-6390-1-git-send-email-andrew.cooper3@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
>>> On 14.11.16 at 12:01, <andrew.cooper3@citrix.com> wrote: > %cs.L may be set in a legacy mode segment, or clear in a compatibility mode > segment; it is not the correct way to check for long mode being active. > > Both of these situations result in incorrect visibility of the SYSCALL feature > in CPUID, and by extension, incorrect behaviour in hvm_efer_valid(). > > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com>
On Mon, Nov 14, 2016 at 11:01:25AM +0000, Andrew Cooper wrote: > %cs.L may be set in a legacy mode segment, or clear in a compatibility mode > segment; it is not the correct way to check for long mode being active. > > Both of these situations result in incorrect visibility of the SYSCALL feature > in CPUID, and by extension, incorrect behaviour in hvm_efer_valid(). > > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Both patches: Release-acked-by: Wei Liu <wei.liu2@citrix.com>
> From: Andrew Cooper [mailto:andrew.cooper3@citrix.com] > Sent: Monday, November 14, 2016 7:01 PM > > %cs.L may be set in a legacy mode segment, or clear in a compatibility mode > segment; it is not the correct way to check for long mode being active. > > Both of these situations result in incorrect visibility of the SYSCALL feature > in CPUID, and by extension, incorrect behaviour in hvm_efer_valid(). > > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Acked-by: Kevin Tian <kevin.tian@intel.com>
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index 9a8f694..a18db28 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -2407,7 +2407,6 @@ static void vmx_cpuid_intercept( unsigned int *ecx, unsigned int *edx) { unsigned int input = *eax; - struct segment_register cs; struct vcpu *v = current; hvm_cpuid(input, eax, ebx, ecx, edx); @@ -2416,8 +2415,7 @@ static void vmx_cpuid_intercept( { case 0x80000001: /* SYSCALL is visible iff running in long mode. */ - vmx_get_segment_register(v, x86_seg_cs, &cs); - if ( cs.attr.fields.l ) + if ( hvm_long_mode_enabled(v) ) *edx |= cpufeat_mask(X86_FEATURE_SYSCALL); else *edx &= ~(cpufeat_mask(X86_FEATURE_SYSCALL));
%cs.L may be set in a legacy mode segment, or clear in a compatibility mode segment; it is not the correct way to check for long mode being active. Both of these situations result in incorrect visibility of the SYSCALL feature in CPUID, and by extension, incorrect behaviour in hvm_efer_valid(). Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> --- CC: Jan Beulich <JBeulich@suse.com> CC: Wei Liu <wei.liu2@citrix.com> CC: Jun Nakajima <jun.nakajima@intel.com> CC: Kevin Tian <kevin.tian@intel.com> --- xen/arch/x86/hvm/vmx/vmx.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)