Messages in this thread | | | From | Steve Rutherford <> | Date | Mon, 6 Apr 2020 18:22:44 -0700 | Subject | Re: [PATCH v6 07/14] KVM: x86: Add AMD SEV specific Hypercall3 |
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On Thu, Apr 2, 2020 at 4:56 PM Krish Sadhukhan <krish.sadhukhan@oracle.com> wrote: > > > On 3/29/20 11:21 PM, Ashish Kalra wrote: > > From: Brijesh Singh <Brijesh.Singh@amd.com> > > > > KVM hypercall framework relies on alternative framework to patch the > > VMCALL -> VMMCALL on AMD platform. If a hypercall is made before > > apply_alternative() > > s/apply_alternative/apply_alternatives/ > > is called then it defaults to VMCALL. The approach > > works fine on non SEV guest. A VMCALL would causes #UD, and hypervisor > > will be able to decode the instruction and do the right things. But > > when SEV is active, guest memory is encrypted with guest key and > > hypervisor will not be able to decode the instruction bytes. > > > > Add SEV specific hypercall3, it unconditionally uses VMMCALL. The hypercall > > will be used by the SEV guest to notify encrypted pages to the hypervisor. > > > > Cc: Thomas Gleixner <tglx@linutronix.de> > > Cc: Ingo Molnar <mingo@redhat.com> > > Cc: "H. Peter Anvin" <hpa@zytor.com> > > Cc: Paolo Bonzini <pbonzini@redhat.com> > > Cc: "Radim Krčmář" <rkrcmar@redhat.com> > > Cc: Joerg Roedel <joro@8bytes.org> > > Cc: Borislav Petkov <bp@suse.de> > > Cc: Tom Lendacky <thomas.lendacky@amd.com> > > Cc: x86@kernel.org > > Cc: kvm@vger.kernel.org > > Cc: linux-kernel@vger.kernel.org > > Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> > > Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> > > --- > > arch/x86/include/asm/kvm_para.h | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h > > index 9b4df6eaa11a..6c09255633a4 100644 > > --- a/arch/x86/include/asm/kvm_para.h > > +++ b/arch/x86/include/asm/kvm_para.h > > @@ -84,6 +84,18 @@ static inline long kvm_hypercall4(unsigned int nr, unsigned long p1, > > return ret; > > } > > > > +static inline long kvm_sev_hypercall3(unsigned int nr, unsigned long p1, > > + unsigned long p2, unsigned long p3) > > +{ > > + long ret; > > + > > + asm volatile("vmmcall" > > + : "=a"(ret) > > + : "a"(nr), "b"(p1), "c"(p2), "d"(p3) > > + : "memory"); > > + return ret; > > +} > > + > > #ifdef CONFIG_KVM_GUEST > > bool kvm_para_available(void); > > unsigned int kvm_arch_para_features(void); > Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Nit: I'd personally have named this kvm_vmmcall3, since it's about invoking a particular instruction. The usage happens to be for SEV.
Reviewed-by: Steve Rutherford <srutherford@google.com>
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