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From: Paolo Bonzini <pbonzini@redhat.com>
To: Jim Mattson <jmattson@google.com>
Cc: "Liran Alon" <liran.alon@oracle.com>,
	dwmw@amazon.co.uk,
	"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
	"the arch/x86 maintainers" <x86@kernel.org>,
	bp@alien8.de, "Nadav Amit" <nadav.amit@gmail.com>,
	"Tom Lendacky" <thomas.lendacky@amd.com>,
	aliguori@amazon.com, "Arjan van de Ven" <arjan@linux.intel.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"kvm list" <kvm@vger.kernel.org>
Subject: Re: [PATCH 3/8] kvm: vmx: pass MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD down to the guest
Date: Wed, 10 Jan 2018 18:16:09 +0100	[thread overview]
Message-ID: <4ceeadb7-61c0-e5b9-867d-16c2bedcabc5@redhat.com> (raw)
In-Reply-To: <CALMp9eSj11tFeSRXDB5xAj6zPxNG=yoqOPbRNxkdjzgG3Cjc4w@mail.gmail.com>

On 10/01/2018 18:14, Jim Mattson wrote:
>>> If (a) is true, does "IBRS ALL THE TIME" usage is basically a CPU
>>> change to just create all BTB/BHB entries to be tagged with
>>> prediction-mode at creation-time and that tag to be compared to current
>>> prediction-mode when CPU attempts to use BTB/BHB?
>>
>> I hope so, and I hope said prediction mode includes PCID/VPID too.
>
> Branch prediction entries should probably be tagged with PCID, VPID,
> EP4TA, and thread ID...the same things used to tag TLB contexts.

But if so, I don't see the need for IBPB.

Paolo

  reply	other threads:[~2018-01-10 17:16 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-10 16:19 Liran Alon
2018-01-10 16:27 ` Paolo Bonzini
2018-01-10 17:14   ` Jim Mattson
2018-01-10 17:16     ` Paolo Bonzini [this message]
2018-01-10 17:23       ` Nadav Amit
2018-01-10 17:32         ` Jim Mattson
2018-01-10 16:47 ` David Woodhouse
  -- strict thread matches above, loose matches on Subject: below --
2018-01-10 16:51 Liran Alon
2018-01-10 17:07 ` David Woodhouse
2018-01-10  0:33 Liran Alon
2018-01-09 16:48 Liran Alon
2018-01-09 16:57 ` Paolo Bonzini
2018-01-10  5:03   ` Nadav Amit
2018-01-10 13:20     ` Paolo Bonzini
2018-01-10 14:06       ` Arjan van de Ven
2018-01-10 14:28         ` Paolo Bonzini
2018-01-10 15:41           ` Konrad Rzeszutek Wilk
2018-01-10 15:45             ` Paolo Bonzini
2018-01-10 15:48             ` Woodhouse, David
2018-01-10 15:56               ` Paolo Bonzini
2018-01-10 16:05                 ` David Woodhouse
2018-01-12 23:17     ` Jim Mattson
2018-01-12 23:19       ` Nadav Amit
2018-01-09 16:06 Liran Alon
2018-01-09 12:03 [PATCH v2 0/8] KVM: x86: expose CVE-2017-5715 ("Spectre variant 2") mitigations to guest Paolo Bonzini
2018-01-09 12:03 ` [PATCH 3/8] kvm: vmx: pass MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD down to the guest Paolo Bonzini
2018-01-13 10:16   ` Longpeng (Mike)
2018-01-15  9:23     ` Paolo Bonzini
2018-01-15  9:34       ` Thomas Gleixner

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