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From: Ingo Molnar <mingo@kernel.org>
To: David Woodhouse <dwmw@amazon.co.uk>
Cc: tglx@linutronix.de, karahmed@amazon.de, sironi@amazon.de,
	x86@kernel.org, kvm@vger.kernel.org,
	torvalds@linux-foundation.org, pbonzini@redhat.com,
	linux-kernel@vger.kernel.org, bp@alien8.de, peterz@infradead.org,
	jmattson@google.com, rkrcmar@redhat.com,
	arjan.van.de.ven@intel.com, dave.hansen@intel.com
Subject: Re: [PATCH v2 5/6] KVM/nVMX: Set the CPU_BASED_USE_MSR_BITMAPS if we have a valid L02 MSR bitmap
Date: Sun, 11 Feb 2018 11:19:24 +0100
Message-ID: <20180211101924.vztfslwqoh7km6q2@gmail.com> (raw)
In-Reply-To: <1518305967-31356-6-git-send-email-dwmw@amazon.co.uk>


* David Woodhouse <dwmw@amazon.co.uk> wrote:

> From: KarimAllah Ahmed <karahmed@amazon.de>
> 
> We either clear the CPU_BASED_USE_MSR_BITMAPS and end up intercepting all
> MSR accesses or create a valid L02 MSR bitmap and use that. This decision
> has to be made every time we evaluate whether we are going to generate the
> L02 MSR bitmap.
> 
> Before commit 086e7d4118cc ("KVM: VMX: Allow direct access to MSR_IA32_SPEC_CTRL")
> this was probably OK since the decision was always identical. This is no
> longer the case now since the MSR bitmap might actually change once we
> decide to not intercept SPEC_CTRL and PRED_CMD.

Note, I fixed the changelog to refer to the correct upstream SHA1, which is:

  d28b387fb74d: KVM/VMX: Allow direct access to MSR_IA32_SPEC_CTRL

Thanks,

	Ingo

  reply index

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-10 23:39 [PATCH v2 0/6] Spectre v2 updates David Woodhouse
2018-02-10 23:39 ` [PATCH v2 1/6] x86/speculation: Update Speculation Control microcode blacklist David Woodhouse
2018-02-12  9:50   ` Darren Kenny
2018-02-12 14:16   ` David Woodhouse
2018-02-12 14:32     ` Thomas Gleixner
2018-02-10 23:39 ` [PATCH v2 2/6] Revert "x86/speculation: Simplify indirect_branch_prediction_barrier()" David Woodhouse
2018-02-10 23:39 ` [PATCH v2 3/6] KVM: x86: Reduce retpoline performance impact in slot_handle_level_range() David Woodhouse
2018-02-10 23:39 ` [PATCH v2 4/6] X86/nVMX: Properly set spec_ctrl and pred_cmd before merging MSRs David Woodhouse
2018-02-10 23:39 ` [PATCH v2 5/6] KVM/nVMX: Set the CPU_BASED_USE_MSR_BITMAPS if we have a valid L02 MSR bitmap David Woodhouse
2018-02-11 10:19   ` Ingo Molnar [this message]
     [not found]     ` <1518345844.3677.365.camel@amazon.co.uk>
2018-02-11 10:55       ` Ingo Molnar
2018-02-10 23:39 ` [PATCH v2 6/6] x86/speculation: Use IBRS if available before calling into firmware David Woodhouse
2018-02-11 11:46   ` Ingo Molnar
2018-02-11 10:41 ` [PATCH v2 0/6] Spectre v2 updates Ingo Molnar
     [not found] ` <1518362359-1005-1-git-send-email-dwmw@amazon.co.uk>
2018-02-11 18:50   ` [PATCH] x86/speculation: Clean up various Spectre related details Ingo Molnar
2018-02-11 19:25     ` David Woodhouse
2018-02-11 19:43       ` Ingo Molnar
2018-02-12 15:30         ` David Woodhouse
2018-02-13  8:04           ` Ingo Molnar
2018-02-12  8:27 ` [PATCH v2 0/6] Spectre v2 updates Paolo Bonzini
2018-02-13  7:59   ` Ingo Molnar

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