From: Paolo Bonzini <pbonzini@redhat.com>
To: Borislav Petkov <bp@suse.de>
Cc: "Brijesh Singh" <brijesh.singh@amd.com>,
"Sean Christopherson" <sean.j.christopherson@intel.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, "Tom Lendacky" <thomas.lendacky@amd.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
"Radim Krčmář" <rkrcmar@redhat.com>
Subject: Re: [PATCH v6 5/5] x86/kvm: Avoid dynamic allocation of pvclock data when SEV is active
Date: Tue, 11 Sep 2018 13:07:06 +0200 [thread overview]
Message-ID: <cacb6865-e4ad-80c9-7482-23e480a61b0f@redhat.com> (raw)
In-Reply-To: <20180911102504.GC11418@zn.tnic>
On 11/09/2018 12:25, Borislav Petkov wrote:
> On Tue, Sep 11, 2018 at 12:19:13PM +0200, Paolo Bonzini wrote:
>> That's exactly what kvmclock is for, it provides a stable and
>> synchronized clock on top of unsynchronized TSCs. But that's also why
>> you need one struct per vCPU, at least in the synchronized case.
^^^^^^^^^^^^
unsynchronized
>
> Why?
>
> Why can't it be a single pointer to a struct pvclock_vsyscall_time_info
> shared between all vCPUs?
>
> Or does each vCPU write its own specific stuff into it so it has to be
> per-vCPU?
If the host TSCs are unsynchronized then yes, that's what happens. And
you can do live migration from synchronized to unsynchronized.
Paolo
next prev parent reply other threads:[~2018-09-11 11:07 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-07 17:57 [PATCH v6 0/5] x86: Fix SEV guest regression Brijesh Singh
2018-09-07 17:57 ` [PATCH v6 1/5] x86/mm: Restructure sme_encrypt_kernel() Brijesh Singh
2018-09-10 11:32 ` Borislav Petkov
2018-09-07 17:57 ` [PATCH v6 2/5] x86/mm: fix sme_populate_pgd() to update page flags Brijesh Singh
2018-09-10 11:36 ` Borislav Petkov
2018-09-10 12:28 ` Brijesh Singh
2018-09-10 12:32 ` Borislav Petkov
2018-09-07 17:57 ` [PATCH v6 3/5] x86/mm: add .data..decrypted section to hold shared variables Brijesh Singh
2018-09-10 11:54 ` Borislav Petkov
2018-09-10 12:33 ` Brijesh Singh
2018-09-07 17:57 ` [PATCH v6 4/5] x86/kvm: use __decrypted attribute in " Brijesh Singh
2018-09-10 12:04 ` Borislav Petkov
2018-09-10 13:15 ` Sean Christopherson
2018-09-10 13:29 ` Thomas Gleixner
2018-09-10 15:34 ` Borislav Petkov
2018-09-10 12:29 ` Paolo Bonzini
2018-09-10 12:33 ` Borislav Petkov
2018-09-10 12:46 ` Paolo Bonzini
2018-09-07 17:57 ` [PATCH v6 5/5] x86/kvm: Avoid dynamic allocation of pvclock data when SEV is active Brijesh Singh
2018-09-10 12:27 ` Borislav Petkov
2018-09-10 13:15 ` Brijesh Singh
2018-09-10 13:29 ` Sean Christopherson
2018-09-10 15:10 ` Brijesh Singh
2018-09-10 15:28 ` Sean Christopherson
2018-09-10 15:30 ` Brijesh Singh
2018-09-10 16:48 ` Borislav Petkov
2018-09-11 9:26 ` Paolo Bonzini
2018-09-11 10:01 ` Borislav Petkov
2018-09-11 10:19 ` Paolo Bonzini
2018-09-11 10:25 ` Borislav Petkov
2018-09-11 11:07 ` Paolo Bonzini [this message]
2018-09-11 13:55 ` Borislav Petkov
2018-09-11 14:00 ` Paolo Bonzini
2018-09-10 15:53 ` Borislav Petkov
2018-09-10 16:13 ` Sean Christopherson
2018-09-10 16:14 ` Brijesh Singh
2018-09-10 12:28 ` Paolo Bonzini
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