All of lore.kernel.org
 help / color / mirror / Atom feed
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 12:19:13 +0200	[thread overview]
Message-ID: <554c6fb5-0de4-5415-9970-0d09325d718b@redhat.com> (raw)
In-Reply-To: <20180911100142.GA11418@zn.tnic>

On 11/09/2018 12:01, Borislav Petkov wrote:
> On Tue, Sep 11, 2018 at 11:26:21AM +0200, Paolo Bonzini wrote:
>> Usually the kvmclock structs are all the same, but there is support for
>> old machines with inconsistent TSCs (across different sockets typically).
> 
> Would that be a problem, though? Sounds like an "improvement" to me. :-)
> 
> I mean, if we keep using the same TSC across all vCPUs, the guest will
> actually see a single TSC and thus have stable and synchronized TSCs.
> Unlike the host.

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.

Paolo

> I.e., the guest will be better than the host! :-)
> 


  reply	other threads:[~2018-09-11 10:19 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 [this message]
2018-09-11 10:25                       ` Borislav Petkov
2018-09-11 11:07                         ` Paolo Bonzini
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=554c6fb5-0de4-5415-9970-0d09325d718b@redhat.com \
    --to=pbonzini@redhat.com \
    --cc=bp@suse.de \
    --cc=brijesh.singh@amd.com \
    --cc=hpa@zytor.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=rkrcmar@redhat.com \
    --cc=sean.j.christopherson@intel.com \
    --cc=tglx@linutronix.de \
    --cc=thomas.lendacky@amd.com \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.