From: Jim Mattson <jmattson@google.com>
To: Ashish Kalra <Ashish.Kalra@amd.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>,
Joerg Roedel <joro@8bytes.org>, Borislav Petkov <bp@suse.de>,
Tom Lendacky <thomas.lendacky@amd.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
kvm list <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Steve Rutherford <srutherford@google.com>,
Sean Christopherson <seanjc@google.com>,
venu.busireddy@oracle.com, Brijesh Singh <brijesh.singh@amd.com>
Subject: Re: [PATCH v2 1/4] KVM: x86: invert KVM_HYPERCALL to default to VMMCALL
Date: Fri, 23 Apr 2021 09:31:07 -0700 [thread overview]
Message-ID: <CALMp9eTTC0kFbRt8TBC3x8N4mDism-xg3xEFSCPGiGc20pZ3ZQ@mail.gmail.com> (raw)
In-Reply-To: <76ad1a3f7ce817e8d269a6d58293fc128678affc.1619193043.git.ashish.kalra@amd.com>
On Fri, Apr 23, 2021 at 9:00 AM Ashish Kalra <Ashish.Kalra@amd.com> wrote:
>
> From: Ashish Kalra <ashish.kalra@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
> 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.
>
> So invert KVM_HYPERCALL and X86_FEATURE_VMMCALL to default to VMMCALL
> and opt into VMCALL.
>
> 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: 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 | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
> index 338119852512..fda2fe0d1b10 100644
> --- a/arch/x86/include/asm/kvm_para.h
> +++ b/arch/x86/include/asm/kvm_para.h
> @@ -19,7 +19,7 @@ static inline bool kvm_check_and_clear_guest_paused(void)
> #endif /* CONFIG_KVM_GUEST */
>
> #define KVM_HYPERCALL \
> - ALTERNATIVE("vmcall", "vmmcall", X86_FEATURE_VMMCALL)
> + ALTERNATIVE("vmmcall", "vmcall", X86_FEATURE_VMCALL)
>
> /* For KVM hypercalls, a three-byte sequence of either the vmcall or the vmmcall
> * instruction. The hypervisor may replace it with something else but only the
> --
> 2.17.1
>
Won't this result in the same problem when Intel implements full VM encryption?
next prev parent reply other threads:[~2021-04-23 16:31 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-23 15:57 [PATCH v2 0/4] Add guest support for SEV live migration Ashish Kalra
2021-04-23 15:58 ` [PATCH v2 1/4] KVM: x86: invert KVM_HYPERCALL to default to VMMCALL Ashish Kalra
2021-04-23 16:31 ` Jim Mattson [this message]
2021-04-23 17:44 ` Sean Christopherson
2021-04-23 15:58 ` [PATCH v2 2/4] mm: x86: Invoke hypercall when page encryption status is changed Ashish Kalra
2021-05-12 13:15 ` Borislav Petkov
2021-05-12 15:51 ` Sean Christopherson
2021-05-12 16:23 ` Borislav Petkov
2021-05-13 6:57 ` Ashish Kalra
2021-05-13 8:40 ` Paolo Bonzini
2021-05-13 13:49 ` Tom Lendacky
2021-05-13 4:34 ` Ashish Kalra
2021-05-14 7:33 ` Borislav Petkov
2021-05-14 8:03 ` Paolo Bonzini
2021-05-14 9:05 ` Ashish Kalra
2021-05-14 9:34 ` Borislav Petkov
2021-05-14 10:05 ` Ashish Kalra
2021-05-14 10:38 ` Borislav Petkov
2021-05-18 2:01 ` Steve Rutherford
2021-05-19 12:06 ` Ashish Kalra
2021-05-19 13:44 ` Paolo Bonzini
2021-05-14 9:57 ` Paolo Bonzini
2021-05-14 9:24 ` Borislav Petkov
2021-05-14 9:33 ` Ashish Kalra
2021-05-19 23:29 ` Andy Lutomirski
2021-05-19 23:44 ` Sean Christopherson
2021-04-23 15:59 ` [PATCH v2 3/4] EFI: Introduce the new AMD Memory Encryption GUID Ashish Kalra
2021-05-12 13:19 ` Borislav Petkov
2021-05-12 14:53 ` Ard Biesheuvel
2021-05-13 4:36 ` Ashish Kalra
2021-04-23 15:59 ` [PATCH v2 4/4] x86/kvm: Add guest support for detecting and enabling SEV Live Migration feature Ashish Kalra
2021-04-30 7:19 ` [PATCH v2 0/4] Add guest support for SEV live migration Ashish Kalra
2021-04-30 7:40 ` Paolo Bonzini
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