From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <seanjc@google.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
srutherford@google.com, joro@8bytes.org, brijesh.singh@amd.com,
thomas.lendacky@amd.com, ashish.kalra@amd.com,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Borislav Petkov <bp@suse.de>,
x86@kernel.org
Subject: Re: [PATCH v3 2/2] KVM: X86: Introduce KVM_HC_PAGE_ENC_STATUS hypercall
Date: Tue, 4 May 2021 22:27:58 +0200 [thread overview]
Message-ID: <f7300393-6527-005f-d824-eed5f7f2f8a8@redhat.com> (raw)
In-Reply-To: <YJF/3d+VBfJKqXV4@google.com>
On 04/05/21 19:09, Sean Christopherson wrote:
> On Sat, May 01, 2021, Paolo Bonzini wrote:
>> - make it completely independent from migration, i.e. it's just a facet of
>> MSR_KVM_PAGE_ENC_STATUS saying whether the bitmap is up-to-date. It would
>> use CPUID bit as the encryption status bitmap and have no code at all in KVM
>> (userspace needs to set up the filter and implement everything).
>
> If the bit is purely a "page encryption status is up-to-date", what about
> overloading KVM_HC_PAGE_ENC_STATUS to handle that status update as well? That
> would eliminate my biggest complaint about having what is effectively a single
> paravirt feature split into two separate, but intertwined chunks of ABI.
It's true that they are intertwined, but I dislike not having a way to
read the current state.
Paolo
>
> #define KVM_HC_PAGE_ENC_UPDATE 12
>
> #define KVM_HC_PAGE_ENC_REGION_UPDATE 0 /* encrypted vs. plain text */
> #define KVM_HC_PAGE_ENC_STATUS_UPDATE 1 /* up-to-date vs. stale */
>
> ret = -KVM_ENOSYS;
> if (!vcpu->kvm->arch.hypercall_exit_enabled)
> break;
>
> ret = -EINVAL;
> if (a0 == KVM_HC_PAGE_ENC_REGION_UPDATE) {
> u64 gpa = a1, npages = a2;
>
> if (!PAGE_ALIGNED(gpa) || !npages ||
> gpa_to_gfn(gpa) + npages <= gpa_to_gfn(gpa))
> break;
> } else if (a0 != KVM_HC_PAGE_ENC_STATUS_UPDATE) {
> break;
> }
>
> vcpu->run->exit_reason = KVM_EXIT_HYPERCALL;
> vcpu->run->hypercall.nr = KVM_HC_PAGE_ENC_STATUS;
> vcpu->run->hypercall.args[0] = a0;
> vcpu->run->hypercall.args[1] = a1;
> vcpu->run->hypercall.args[2] = a2;
> vcpu->run->hypercall.args[3] = a3;
> vcpu->run->hypercall.longmode = op_64_bit;
> vcpu->arch.complete_userspace_io = complete_hypercall_exit;
> return 0;
>
next prev parent reply other threads:[~2021-05-04 20:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 10:47 [PATCH v3 0/2] KVM: x86: guest interface for SEV live migration Paolo Bonzini
2021-04-29 10:47 ` [PATCH v3 1/2] KVM: x86: add MSR_KVM_MIGRATION_CONTROL Paolo Bonzini
2021-04-29 10:47 ` [PATCH v3 2/2] KVM: X86: Introduce KVM_HC_PAGE_ENC_STATUS hypercall Paolo Bonzini
2021-04-30 20:10 ` Sean Christopherson
2021-05-01 9:01 ` Paolo Bonzini
2021-05-03 23:22 ` Steve Rutherford
2021-05-04 8:06 ` Paolo Bonzini
2021-05-04 17:09 ` Sean Christopherson
2021-05-04 20:27 ` Paolo Bonzini [this message]
2021-05-04 20:33 ` Sean Christopherson
2021-05-04 20:56 ` Paolo Bonzini
2021-05-04 21:16 ` Steve Rutherford
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