On Thu, Apr 08, 2021 at 04:44:23PM +0200, Vitaly Kuznetsov wrote: > Siddharth Chandrasekaran <sidcha@xxxxxxxxx> writes: > > On Thu, Apr 08, 2021 at 02:05:53PM +0200, Vitaly Kuznetsov wrote: > >> Siddharth Chandrasekaran <sidcha@xxxxxxxxx> writes: > >> > Now that all extant hypercalls that can use XMM registers (based on > >> > spec) for input/outputs are patched to support them, we can start > >> > advertising this feature to guests. > >> > > >> > Cc: Alexander Graf <graf@xxxxxxxxxx> > >> > Cc: Evgeny Iakovlev <eyakovl@xxxxxxxxx> > >> > Signed-off-by: Siddharth Chandrasekaran <sidcha@xxxxxxxxx> > >> > --- > >> > arch/x86/include/asm/hyperv-tlfs.h | 4 ++-- > >> > arch/x86/kvm/hyperv.c | 1 + > >> > 2 files changed, 3 insertions(+), 2 deletions(-) > >> > > >> > diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h > >> > index e6cd3fee562b..1f160ef60509 100644 > >> > --- a/arch/x86/include/asm/hyperv-tlfs.h > >> > +++ b/arch/x86/include/asm/hyperv-tlfs.h > >> > @@ -49,10 +49,10 @@ > >> > /* Support for physical CPU dynamic partitioning events is available*/ > >> > #define HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE BIT(3) > >> > /* > >> > - * Support for passing hypercall input parameter block via XMM > >> > + * Support for passing hypercall input and output parameter block via XMM > >> > * registers is available > >> > */ > >> > -#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE BIT(4) > >> > +#define HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE BIT(4) | BIT(15) > >> > >> TLFS 6.0b states that there are two distinct bits for input and output: > >> > >> CPUID Leaf 0x40000003.EDX: > >> Bit 4: support for passing hypercall input via XMM registers is available. > >> Bit 15: support for returning hypercall output via XMM registers is available. > >> > >> and HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE is not currently used > >> anywhere, I'd suggest we just rename > >> > >> HV_X64_HYPERCALL_PARAMS_XMM_AVAILABLE to HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE > >> and add HV_X64_HYPERCALL_XMM_OUTPUT_AVAILABLE (bit 15). > > > > That is how I had it initially; but then noticed that we would never > > need to use either of them separately. So it seemed like a reasonable > > abstraction to put them together. > > > > Actually, we may. In theory, KVM userspace may decide to expose just > one of these two to the guest as it is not obliged to copy everything > from KVM_GET_SUPPORTED_HV_CPUID so we will need separate > guest_cpuid_has() checks. Looks like guest_cpuid_has() check is for x86 CPU features only (if I'm not mistaken) and I don't see a suitable alternative that looks into vcpu->arch.cpuid_entries[]. So I plan to add a new method hv_guest_cpuid_has() in hyperv.c to have this check; does that sound right to you? If you can give a quick go-ahead, I'll make the changes requested so far and send v2 this series. Thanks. ~ Sid. Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879
