On 03/28/2011 03:56 PM, Roedel, Joerg wrote:
On Mon, Mar 28, 2011 at 08:35:54AM -0400, Avi Kivity wrote:
> On 03/28/2011 12:46 PM, Joerg Roedel wrote:
> > This patch add intercept checks into the KVM instruction
> > emulator to check for the 8 instructions that access the
> > descriptor table addresses.
> >
> > +static struct opcode group6[] = {
> > + DI(ModRM, sldt),
> > + DI(ModRM, str),
> > + DI(ModRM | Priv, lldt),
> > + DI(ModRM | Priv, ltr),
> > + N, N, N, N,
> > +};
> > +
> > static struct group_dual group7 = { {
> > - N, N, DI(ModRM | SrcMem | Priv, lgdt), DI(ModRM | SrcMem | Priv, lidt),
> > + DI(ModRM | DstMem | Priv, sgdt), DI(ModRM | DstMem | Priv, sidt),
> > + DI(ModRM | SrcMem | Priv, lgdt), DI(ModRM | SrcMem | Priv, lidt),
>
> | Mov, to avoid RMW for SIDT, for example. Also need to indicate the
> operand size correctly.
>
> > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> > index 381b038..485a09f 100644
> > --- a/arch/x86/kvm/svm.c
> > +++ b/arch/x86/kvm/svm.c
> > @@ -3871,6 +3871,10 @@ static void svm_fpu_deactivate(struct kvm_vcpu *vcpu)
> > #define POST_EX(exit) { .exit_code = (exit), \
> > .stage = X86_ICPT_POST_EXCEPT, \
> > .valid = true }
> > +#define POST_MEM(exit) { .exit_code = (exit), \
> > + .stage = X86_ICPT_POST_MEMACCESS, \
> > + .valid = true }
> > +
> >
> > static struct __x86_intercept {
> > u32 exit_code;
> > @@ -3884,9 +3888,18 @@ static struct __x86_intercept {
> > [x86_intercept_smsw] = POST_EX(SVM_EXIT_READ_CR0),
> > [x86_intercept_dr_read] = POST_EX(SVM_EXIT_READ_DR0),
> > [x86_intercept_dr_write] = POST_EX(SVM_EXIT_WRITE_DR0),
> > + [x86_intercept_sldt] = POST_MEM(SVM_EXIT_LDTR_READ),
> > + [x86_intercept_str] = POST_MEM(SVM_EXIT_TR_READ),
> > + [x86_intercept_lldt] = POST_MEM(SVM_EXIT_LDTR_WRITE),
> > + [x86_intercept_ltr] = POST_MEM(SVM_EXIT_TR_WRITE),
> > + [x86_intercept_sgdt] = POST_MEM(SVM_EXIT_GDTR_READ),
> > + [x86_intercept_sidt] = POST_MEM(SVM_EXIT_IDTR_READ),
> > + [x86_intercept_lgdt] = POST_MEM(SVM_EXIT_GDTR_WRITE),
> > + [x86_intercept_lidt] = POST_MEM(SVM_EXIT_IDTR_WRITE),
> > };
>
> Spec says POST_EX()?
Well, not entirely clear. Spec says that #GP takes precedence before the
intercept and the intruction reference says the #GP fires if the
supplied address is not within segment limits or the segment itself is
not valid, which, in my interpretation, made them POST_MEM.
My interpretation would be that a #GP(0) due to CPL check takes
precedence over the intercept, which takes precedence over a
#GP(selector) due to the actual memory reference.
--
error compiling committee.c: too many arguments to function
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