linux-kernel - [RFC PATCH 26/67] KVM: x86: Add kvm_x86_ops .cache_gprs() and .flush

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Date:   Mon, 16 Nov 2020 10:26:11 -0800
From:   isaku.yamahata@...el.com
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     isaku.yamahata@...el.com, isaku.yamahata@...il.com,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: [RFC PATCH 26/67] KVM: x86: Add kvm_x86_ops .cache_gprs() and .flush_gprs()

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>
---
 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 7537ba0bada2..01c78eeefef4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1130,6 +1130,8 @@ 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 a1c57d1eb460..22e956f01ddc 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9385,6 +9385,9 @@ 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
@@ -9459,6 +9462,9 @@ 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);
 }
 
-- 
2.17.1