Messages in this thread Patch in this message | | | Date | Thu, 2 Apr 2020 17:36:53 -0500 | From | Venu Busireddy <> | Subject | Re: [PATCH v6 07/14] KVM: x86: Add AMD SEV specific Hypercall3 |
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On 2020-03-30 06:21:52 +0000, 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() is called then it defaults to VMCALL. The approach > works fine on non SEV guest. A VMCALL would causes #UD, and hypervisor ^^^^^^ cause > 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 ^^ which > 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>
Reviewed-by: Venu Busireddy <venu.busireddy@oracle.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); > -- > 2.17.1 >
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