On Thu, Feb 28, 2019 at 08:25:12AM -0800, Sean Christopherson wrote: > On Mon, Feb 25, 2019 at 09:27:15PM +0800, Yang Weijiang wrote: > > For Guest XSS, right now, only bit 11(user states) and bit 12 > > (supervisor states) are supported, if other bits are being set, > > need to modify KVM_SUPPORTED_XSS macro to have support. > > The changelog should describe what the change does directly. Referencing > specific bits implies that the code is explicitly checking for said bits, > which it does not. And there's no need to advise readers on how to add > more bits in the future, e.g. the KVM_SUPPORTED_XSS macro may not exist > the next time new bits are added. Just cover what the patch does and why. > > Something like: > > KVM: x86: Allow the guest to set supported bits in XSS > > ...now that KVM supports setting CET related bits. Previously, KVM did > not support setting any bits in XSS and so hardcoded its check to inject > a #GP if the guest attempted to write a non-zero value to IA32_XSS. > good point! Will change these description. > > > > Signed-off-by: Zhang Yi Z <yi.z.zhang@xxxxxxxxxxxxxxx> > > Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx> > > --- > > arch/x86/kvm/vmx.c | 8 +++++--- > > 1 file changed, 5 insertions(+), 3 deletions(-) > > > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > > index d32cee9ee079..68908ed7b151 100644 > > --- a/arch/x86/kvm/vmx.c > > +++ b/arch/x86/kvm/vmx.c > > @@ -47,6 +47,7 @@ > > #include <asm/virtext.h> > > #include <asm/mce.h> > > #include <asm/fpu/internal.h> > > +#include <asm/fpu/types.h> > > #include <asm/perf_event.h> > > #include <asm/debugreg.h> > > #include <asm/kexec.h> > > @@ -4336,12 +4337,13 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > > case MSR_IA32_XSS: > > if (!vmx_xsaves_supported()) > > return 1; > > + > > /* > > - * The only supported bit as of Skylake is bit 8, but > > - * it is not supported on KVM. > > + * Check bits being set are supported in KVM. > > I'd drop the comment altogether, it's pretty obvious from the code that > were checking which bits are supported. you won't see these redundancies in next version ;) > > */ > > - if (data != 0) > > + if (data & ~kvm_supported_xss()) > > return 1; > > + > > vcpu->arch.ia32_xss = data; > > if (vcpu->arch.ia32_xss != host_xss) > > add_atomic_switch_msr(vmx, MSR_IA32_XSS, > > -- > > 2.17.1 > >
