[RFC PATCH v3 24/59] KVM: x86: Add kvm_x86_ops .cache_gprs() and .flush_gprs()

[isaku . yamahata]

From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>

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@xxxxxxx>
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
 arch/x86/include/asm/kvm-x86-ops.h | 2 ++
 arch/x86/include/asm/kvm_host.h    | 2 ++
 arch/x86/kvm/x86.c                 | 4 ++++
 3 files changed, 8 insertions(+)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index 4aa0a1c10b84..30754f2b8a99 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -45,6 +45,8 @@ KVM_X86_OP(get_gdt)
 KVM_X86_OP(set_gdt)
 KVM_X86_OP(sync_dirty_debug_regs)
 KVM_X86_OP(set_dr7)
+KVM_X86_OP_NULL(cache_gprs)
+KVM_X86_OP_NULL(flush_gprs)
 KVM_X86_OP(cache_reg)
 KVM_X86_OP(get_rflags)
 KVM_X86_OP(set_rflags)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 5ed07f31459e..f12eec3f05ab 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1352,6 +1352,8 @@ 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 0221ef691a15..2e0bccbd3c44 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10293,6 +10293,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
 static void __get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
 {
+	static_call_cond(kvm_x86_cache_gprs)(vcpu);
+
 	if (vcpu->arch.emulate_regs_need_sync_to_vcpu) {
 		/*
 		 * We are here if userspace calls get_regs() in the middle of
@@ -10367,6 +10369,8 @@ static void __set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
 
 	vcpu->arch.exception.pending = false;
 
+	static_call_cond(kvm_x86_flush_gprs);
+
 	kvm_make_request(KVM_REQ_EVENT, vcpu);
 }
 
-- 
2.25.1