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Subject: Re: [PATCH v4 0/4] Add support for XMM fast hypercalls
To:     Siddharth Chandrasekaran <sidcha@amazon.de>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>
Cc:     Siddharth Chandrasekaran <sidcha.dev@gmail.com>,
        Alexander Graf <graf@amazon.com>,
        Evgeny Iakovlev <eyakovl@amazon.de>,
        Liran Alon <liran@amazon.com>,
        Ioannis Aslanidis <iaslan@amazon.de>,
        linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
References: <cover.1622019133.git.sidcha@amazon.de>
 <20210630115559.GA32360@u366d62d47e3651.ant.amazon.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <f318fd42-6b98-1a82-f334-d05f4e6cb715@redhat.com>
Date:   Tue, 6 Jul 2021 17:04:59 +0200
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On 30/06/21 13:56, Siddharth Chandrasekaran wrote:
> 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?

They are part of 5.14 already. :)

Paolo