| Message ID | 5CEBA3B80200007800232856@prv1-mh.provo.novell.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | x86/kvm/VMX: drop bad asm() clobber from nested_vmx_check_vmentry_hw() | expand |
On Mon, May 27, 2019 at 02:45:44AM -0600, Jan Beulich wrote: > While upstream gcc doesn't detect conflicts on cc (yet), it really > should, and hence "cc" should not be specified for asm()-s also having > "=@cc<cond>" outputs. (It is quite pointless anyway to specify a "cc" > clobber in x86 inline assembly, since the compiler assumes it to be > always clobbered, and has no means [yet] to suppress this behavior.) > > Signed-off-by: Jan Beulich <jbeulich@suse.com> FWIW (mostly to satisfy my curiosity): Fixes: bbc0b8239257 ("KVM: nVMX: Capture VM-Fail via CC_{SET,OUT} in nested early checks") Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com> > > --- a/arch/x86/kvm/vmx/nested.c > +++ b/arch/x86/kvm/vmx/nested.c > @@ -2781,7 +2781,7 @@ static int nested_vmx_check_vmentry_hw(s > [launched]"i"(offsetof(struct loaded_vmcs, launched)), > [host_state_rsp]"i"(offsetof(struct loaded_vmcs, host_state.rsp)), > [wordsize]"i"(sizeof(ulong)) > - : "cc", "memory" > + : "memory" > ); > > if (vmx->msr_autoload.host.nr) > >
On 27/05/19 10:45, Jan Beulich wrote: > While upstream gcc doesn't detect conflicts on cc (yet), it really > should, and hence "cc" should not be specified for asm()-s also having > "=@cc<cond>" outputs. (It is quite pointless anyway to specify a "cc" > clobber in x86 inline assembly, since the compiler assumes it to be > always clobbered, and has no means [yet] to suppress this behavior.) > > Signed-off-by: Jan Beulich <jbeulich@suse.com> > > --- a/arch/x86/kvm/vmx/nested.c > +++ b/arch/x86/kvm/vmx/nested.c > @@ -2781,7 +2781,7 @@ static int nested_vmx_check_vmentry_hw(s > [launched]"i"(offsetof(struct loaded_vmcs, launched)), > [host_state_rsp]"i"(offsetof(struct loaded_vmcs, host_state.rsp)), > [wordsize]"i"(sizeof(ulong)) > - : "cc", "memory" > + : "memory" > ); > > if (vmx->msr_autoload.host.nr) > > Queued, thanks. Paolo
--- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -2781,7 +2781,7 @@ static int nested_vmx_check_vmentry_hw(s [launched]"i"(offsetof(struct loaded_vmcs, launched)), [host_state_rsp]"i"(offsetof(struct loaded_vmcs, host_state.rsp)), [wordsize]"i"(sizeof(ulong)) - : "cc", "memory" + : "memory" ); if (vmx->msr_autoload.host.nr)
While upstream gcc doesn't detect conflicts on cc (yet), it really should, and hence "cc" should not be specified for asm()-s also having "=@cc<cond>" outputs. (It is quite pointless anyway to specify a "cc" clobber in x86 inline assembly, since the compiler assumes it to be always clobbered, and has no means [yet] to suppress this behavior.) Signed-off-by: Jan Beulich <jbeulich@suse.com>