| Message ID | 1482337930-16744-1-git-send-email-andrew.cooper3@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
>>> On 21.12.16 at 17:32, <andrew.cooper3@citrix.com> wrote: > The bracketing of x86_emulate() calling the ops->vmfunc() hook is wrong with > respect to the assignment to rc, which can trip the new assertions in > x86_emulate_wrapper(). > > The hvmemul_vmfunc() hook should only raise #UD if X86EMUL_EXCEPTION is > returned. This is only a latent bug at the moment. > > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> > --- a/xen/arch/x86/hvm/emulate.c > +++ b/xen/arch/x86/hvm/emulate.c > @@ -1653,7 +1653,7 @@ static int hvmemul_vmfunc( > if ( !hvm_funcs.altp2m_vcpu_emulate_vmfunc ) > return X86EMUL_UNHANDLEABLE; > rc = hvm_funcs.altp2m_vcpu_emulate_vmfunc(ctxt->regs); > - if ( rc != X86EMUL_OKAY ) > + if ( rc == X86EMUL_EXCEPTION ) > x86_emul_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC, ctxt); Great - saves me from submitting one of my follow-up patches. Jan
diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c index 24754d3..aa1b716 100644 --- a/xen/arch/x86/hvm/emulate.c +++ b/xen/arch/x86/hvm/emulate.c @@ -1653,7 +1653,7 @@ static int hvmemul_vmfunc( if ( !hvm_funcs.altp2m_vcpu_emulate_vmfunc ) return X86EMUL_UNHANDLEABLE; rc = hvm_funcs.altp2m_vcpu_emulate_vmfunc(ctxt->regs); - if ( rc != X86EMUL_OKAY ) + if ( rc == X86EMUL_EXCEPTION ) x86_emul_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC, ctxt); return rc; diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c index b6d7358..3076c0c 100644 --- a/xen/arch/x86/x86_emulate/x86_emulate.c +++ b/xen/arch/x86/x86_emulate/x86_emulate.c @@ -4463,7 +4463,7 @@ x86_emulate( generate_exception_if(lock_prefix | rep_prefix() | (vex.pfx == vex_66), EXC_UD); fail_if(!ops->vmfunc); - if ( (rc = ops->vmfunc(ctxt) != X86EMUL_OKAY) ) + if ( (rc = ops->vmfunc(ctxt)) != X86EMUL_OKAY ) goto done; goto no_writeback;
The bracketing of x86_emulate() calling the ops->vmfunc() hook is wrong with respect to the assignment to rc, which can trip the new assertions in x86_emulate_wrapper(). The hvmemul_vmfunc() hook should only raise #UD if X86EMUL_EXCEPTION is returned. This is only a latent bug at the moment. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> --- CC: Jan Beulich <JBeulich@suse.com> CC: Paul Durrant <paul.durrant@citrix.com> --- xen/arch/x86/hvm/emulate.c | 2 +- xen/arch/x86/x86_emulate/x86_emulate.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)