On Fri, Apr 09, 2021 at 09:42:41AM +0200, Vitaly Kuznetsov wrote: > Siddharth Chandrasekaran <sidcha@xxxxxxxxx> writes: > > On Thu, Apr 08, 2021 at 04:30:18PM +0000, Wei Liu wrote: > >> On Thu, Apr 08, 2021 at 05:54:43PM +0200, Siddharth Chandrasekaran wrote: > >> > On Thu, Apr 08, 2021 at 05:48:19PM +0200, Paolo Bonzini wrote: > >> > > On 08/04/21 17:40, Siddharth Chandrasekaran wrote: > >> > > > > > > Although the Hyper-v TLFS mentions that a guest cannot use this feature > >> > > > > > > unless the hypervisor advertises support for it, some hypercalls which > >> > > > > > > we plan on upstreaming in future uses them anyway. > >> > > > > > No, please don't do this. Check the feature bit(s) before you issue > >> > > > > > hypercalls which rely on the extended interface. > >> > > > > Perhaps Siddharth should clarify this, but I read it as Hyper-V being > >> > > > > buggy and using XMM arguments unconditionally. > >> > > > The guest is at fault here as it expects Hyper-V to consume arguments > >> > > > from XMM registers for certain hypercalls (that we are working) even if > >> > > > we didn't expose the feature via CPUID bits. > >> > > > >> > > What guest is that? > >> > > >> > It is a Windows Server 2016. > >> > >> Can you be more specific? Are you implementing some hypercalls from > >> TLFS? If so, which ones? > > > > Yes all of them are from TLFS. We are implementing VSM and there are a > > bunch of hypercalls that we have implemented to manage VTL switches, > > memory protection and virtual interrupts. > > Wow, sounds awesome! Do you plan to upstream this work? Yes, that is the plan :-) > > The following 3 hypercalls that use the XMM fast hypercalls are relevant > > to this patch set: > > > > HvCallModifyVtlProtectionMask > > HvGetVpRegisters > > HvSetVpRegisters > > It seems AccessVSM and AccessVpRegisters privilges have implicit > dependency on XMM input/output. This will need to be enforced in KVM > userspace. Noted. ~ 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
