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Subject: RE: [PATCH v4] KVM: x86/xen: Update Xen CPUID Leaf 4 (tsc info) sub-leaves,
 if present
Thread-Topic: [PATCH v4] KVM: x86/xen: Update Xen CPUID Leaf 4 (tsc info) sub-leaves,
 if present
From:   "Durrant, Paul" <pdurrant@amazon.co.uk>
To:     Sean Christopherson <seanjc@google.com>
CC:     "x86@kernel.org" <x86@kernel.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        David Woodhouse <dwmw2@infradead.org>,
        "Paolo Bonzini" <pbonzini@redhat.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        "Joerg Roedel" <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>
Thread-Index: AQHYhkt9PlSgQj3r2kG3c5Kzi5Ybkq1jZe+AgAAAylA=
Date:   Mon, 27 Jun 2022 15:23:54 +0000
Message-ID: <91a4b01e8d9b4b3c9ed43614810e75ce@EX13D32EUC003.ant.amazon.com>
References: <20220622151728.13622-1-pdurrant@amazon.com>
 <YrnKc6RoqDM/At3T@google.com>
In-Reply-To: <YrnKc6RoqDM/At3T@google.com>
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> -----Original Message-----
> From: Sean Christopherson <seanjc@google.com>
> Sent: 27 June 2022 16:19
> To: Durrant, Paul <pdurrant@amazon.co.uk>
> Cc: x86@kernel.org; kvm@vger.kernel.org; linux-kernel@vger.kernel.org; Da=
vid Woodhouse
> <dwmw2@infradead.org>; Paolo Bonzini <pbonzini@redhat.com>; Vitaly Kuznet=
sov <vkuznets@redhat.com>;
> Wanpeng Li <wanpengli@tencent.com>; Jim Mattson <jmattson@google.com>; Jo=
erg Roedel <joro@8bytes.org>;
> Thomas Gleixner <tglx@linutronix.de>; Ingo Molnar <mingo@redhat.com>; Bor=
islav Petkov <bp@alien8.de>;
> Dave Hansen <dave.hansen@linux.intel.com>; H. Peter Anvin <hpa@zytor.com>
> Subject: RE: [EXTERNAL][PATCH v4] KVM: x86/xen: Update Xen CPUID Leaf 4 (=
tsc info) sub-leaves, if
> present
>=20
> CAUTION: This email originated from outside of the organization. Do not c=
lick links or open
> attachments unless you can confirm the sender and know the content is saf=
e.
>=20
>=20
>=20
> On Wed, Jun 22, 2022, Paul Durrant wrote:
> > The scaling information in subleaf 1 should match the values set by KVM=
 in
> > the 'vcpu_info' sub-structure 'time_info' (a.k.a. pvclock_vcpu_time_inf=
o)
> > which is shared with the guest, but is not directly available to the VM=
M.
> > The offset values are not set since a TSC offset is already applied.
> > The TSC frequency should also be set in sub-leaf 2.
> >
> > Cache pointers to the sub-leaves when CPUID is updated by the VMM and
> > populate the relevant information prior to entering the guest.
>=20
> All of my comments about the code still apply.
>=20
> https://lore.kernel.org/all/YrMqtHzNSean+qkh@google.com
>=20

Apologies. Not sure how I missed them; I'll send a response shortly.

> > Signed-off-by: Paul Durrant <pdurrant@amazon.com>
> > ---
> > Cc: David Woodhouse <dwmw2@infradead.org>
>=20
> Cc: can go in the changelog, it's helpful info to carry with the commit a=
s it
> documents who was made aware of the patch, e.g. show who may have had a c=
ance to
> object/review.
>=20
> >
> > v2:
> >  - Make sure sub-leaf pointers are NULLed if the time leaf is removed
> >
> > v3:
> >  - Add leaf limit check in kvm_xen_set_cpuid()
> >
> > v4:
> >  - Update commit comment
>=20
> Please start with the most recent verison and work backardwards, that way=
 reviewers
> can quickly see the delta for _this_ version.  I.e.
>=20
>=20
> v4:
>=20
> v3:
>=20
> v2:
>=20
> v1:

Ok.

  Paul