linux-kernel - Re: [PATCH v2 3/4] KVM: x86: kvm_hv_flush

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Message-ID: <20210412201319.lnohqg6r54p6embb@liuwe-devbox-debian-v2>
Date:   Mon, 12 Apr 2021 20:13:19 +0000
From:   Wei Liu <wei.liu@...nel.org>
To:     Siddharth Chandrasekaran <sidcha@...zon.de>
Cc:     "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>,
        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>,
        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 v2 3/4] KVM: x86: kvm_hv_flush_tlb use inputs from XMM
 registers

On Mon, Apr 12, 2021 at 07:00:16PM +0200, Siddharth Chandrasekaran wrote:
> +
> +static inline void kvm_hv_hypercall_read_xmm(struct kvm_hv_hcall *hc)

Do you really need inline here? The compiler should be smart enough to
inline this function if necessary.

> +{
> +	int reg;
> +
> +	kvm_fpu_get();
> +	for (reg = 0; reg < KVM_HV_HYPERCALL_MAX_XMM_REGISTERS; reg++)
> +		_kvm_read_sse_reg(reg, &hc->xmm[reg]);
> +	kvm_fpu_put();
> +	hc->xmm_dirty = false;

There is no code that sets xmm_dirty to true? What am I missing? I guess
that's because you haven't implemented the hypercalls that need writing
back to guest?

Wei.