From: Borislav Petkov <bp@alien8.de>
To: Ashish Kalra <ashish.kalra@amd.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
seanjc@google.com, tglx@linutronix.de, mingo@redhat.com,
hpa@zytor.com, joro@8bytes.org, thomas.lendacky@amd.com,
x86@kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, srutherford@google.com,
venu.busireddy@oracle.com, brijesh.singh@amd.com
Subject: Re: [PATCH v2 2/4] mm: x86: Invoke hypercall when page encryption status is changed
Date: Fri, 14 May 2021 12:38:27 +0200 [thread overview]
Message-ID: <YJ5TI2LD2PB35QYE@zn.tnic> (raw)
In-Reply-To: <20210514100519.GA21705@ashkalra_ubuntu_server>
On Fri, May 14, 2021 at 10:05:19AM +0000, Ashish Kalra wrote:
> No, actually notify_addr_enc_status_changed() is called whenever a range
> of memory is marked as encrypted or decrypted, so it has nothing to do
> with migration as such.
>
> This is basically modifying the encryption attributes on the page tables
> and correspondingly also making the hypercall to inform the hypervisor about
> page status encryption changes. The hypervisor will use this information
> during an ongoing or future migration, so this information is maintained
> even though migration might never be initiated here.
Doh, ofcourse. This doesn't make it easier.
> The error value cannot be propogated up the callchain directly
> here,
Yeah, my thinking was way wrong here - sorry about that.
> but one possibility is to leverage the hypercall and use Sean's
> proposed hypercall interface to notify the host/hypervisor to block/stop
> any future/ongoing migration.
>
> Or as from Paolo's response, writing 0 to MIGRATION_CONTROL MSR seems
> more ideal.
Ok.
So to sum up: notify_addr_enc_status_changed() should warn but not
because of migration but because regardless, we should tell the users
when page enc attributes updating fails as that is potentially hinting
at a bigger problem so we better make sufficient noise here.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-05-14 10:38 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
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 [this message]
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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