On 08/26/2009 05:15 PM, Roel Kluin wrote:
Op 26-08-09 12:29, Avi Kivity schreef:
Instead of calling vmx_get_segment() (which reads a whole bunch of
vmcs fields), read only the cs selector which contains the cpl.
Signed-off-by: Avi Kivity<avi@xxxxxxxxxx>
Can't we also optimise cs_ss_rpl_check()? (Please review, untested.)
------------->8 ---------------------- 8< --------------------
Instead of calling vmx_get_segment() (which reads a whole bunch of
vmcs fields), read only the cs/ss selectors which contains the rpls.
It's really a slowpath, so I prefer not to touch it. We're likely to
start caching guest segment fields soon, so the less code that reads
them directly, the better.
Signed-off-by: Roel Kluin<roel.kluin@xxxxxxxxx>
---
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 29f9129..5d8512a 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1932,13 +1932,8 @@ static bool ldtr_valid(struct kvm_vcpu *vcpu)
static bool cs_ss_rpl_check(struct kvm_vcpu *vcpu)
{
- struct kvm_segment cs, ss;
-
- vmx_get_segment(vcpu,&cs, VCPU_SREG_CS);
- vmx_get_segment(vcpu,&ss, VCPU_SREG_SS);
-
- return ((cs.selector& SELECTOR_RPL_MASK) ==
- (ss.selector& SELECTOR_RPL_MASK));
+ return ((vmcs_read16(GUEST_CS_SELECTOR)& SELECTOR_RPL_MASK) ==
+ (vmcs_read16(GUEST_SS_SELECTOR)& SELECTOR_RPL_MASK));
}
/*
--
error compiling committee.c: too many arguments to function
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