linux-kernel - Re: [RFC PATCH v2 33/69] KVM: x86: Add kvm_x86_ops .cache_gprs() and .flush

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Message-ID: <71ea2142-b299-0fbf-c6f5-5146ad8370a6@redhat.com>
Date:   Tue, 6 Jul 2021 16:10:56 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     isaku.yamahata@...el.com, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, erdemaktas@...gle.com,
        Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     isaku.yamahata@...il.com,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [RFC PATCH v2 33/69] KVM: x86: Add kvm_x86_ops .cache_gprs() and
 .flush_gprs()

On 03/07/21 00:04, isaku.yamahata@...el.com wrote:
> From: Sean Christopherson <sean.j.christopherson@...el.com>
> 
> Add hooks to cache and flush GPRs and invoke them from KVM_GET_REGS and
> KVM_SET_REGS respecitively.  TDX will use the hooks to read/write GPRs
> from TDX-SEAM on-demand (for debug TDs).
> 
> Cc: Tom Lendacky <thomas.lendacky@....com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> ---
>   arch/x86/include/asm/kvm_host.h | 2 ++
>   arch/x86/kvm/x86.c              | 6 ++++++
>   2 files changed, 8 insertions(+)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 00333af724d7..9791c4bb5198 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1248,6 +1248,8 @@ struct kvm_x86_ops {
>   	void (*set_gdt)(struct kvm_vcpu *vcpu, struct desc_ptr *dt);
>   	void (*sync_dirty_debug_regs)(struct kvm_vcpu *vcpu);
>   	void (*set_dr7)(struct kvm_vcpu *vcpu, unsigned long value);
> +	void (*cache_gprs)(struct kvm_vcpu *vcpu);
> +	void (*flush_gprs)(struct kvm_vcpu *vcpu);
>   	void (*cache_reg)(struct kvm_vcpu *vcpu, enum kvm_reg reg);
>   	unsigned long (*get_rflags)(struct kvm_vcpu *vcpu);
>   	void (*set_rflags)(struct kvm_vcpu *vcpu, unsigned long rflags);
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index c231a88d5946..f7ae0a47e555 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -9850,6 +9850,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>   
>   static void __get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
>   {
> +	if (kvm_x86_ops.cache_gprs)
> +		kvm_x86_ops.cache_gprs(vcpu);
> +
>   	if (vcpu->arch.emulate_regs_need_sync_to_vcpu) {
>   		/*
>   		 * We are here if userspace calls get_regs() in the middle of
> @@ -9924,6 +9927,9 @@ static void __set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
>   
>   	vcpu->arch.exception.pending = false;
>   
> +	if (kvm_x86_ops.flush_gprs)
> +		kvm_x86_ops.flush_gprs(vcpu);
> +
>   	kvm_make_request(KVM_REQ_EVENT, vcpu);
>   }
>   
> 

Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>