linux-kernel - Re: [PATCH v4 0/4] Add support for XMM fast hypercalls

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Message-ID: <20210630115559.GA32360@u366d62d47e3651.ant.amazon.com>
Date:   Wed, 30 Jun 2021 13:56:00 +0200
From:   Siddharth Chandrasekaran <sidcha@...zon.de>
To:     "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
CC:     Siddharth Chandrasekaran <sidcha.dev@...il.com>,
        Alexander Graf <graf@...zon.com>,
        Evgeny Iakovlev <eyakovl@...zon.de>,
        Liran Alon <liran@...zon.com>,
        Ioannis Aslanidis <iaslan@...zon.de>,
        <linux-hyperv@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <kvm@...r.kernel.org>
Subject: Re: [PATCH v4 0/4] Add support for XMM fast hypercalls

On Wed, May 26, 2021 at 10:56:07AM +0200, Siddharth Chandrasekaran wrote:
> Hyper-V supports the use of XMM registers to perform fast hypercalls.
> This allows guests to take advantage of the improved performance of the
> fast hypercall interface even though a hypercall may require more than
> (the current maximum of) two general purpose registers.
> 
> The XMM fast hypercall interface uses an additional six XMM registers
> (XMM0 to XMM5) to allow the caller to pass an input parameter block of
> up to 112 bytes. Hyper-V can also return data back to the guest in the
> remaining XMM registers that are not used by the current hypercall.
> 
> Although the Hyper-v TLFS mentions that a guest cannot use this feature
> unless the hypervisor advertises support for it, some hypercalls which
> we plan on upstreaming in future uses them anyway. This patchset adds
> necessary infrastructure for handling input/output via XMM registers and
> patches kvm_hv_flush_tlb() to use xmm input arguments.

Hi Paolo,

Are you expecting more reviews on these patches? 

Thanks. 

~ Sid



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