[PATCH v3 1/6] KVM: x86: introduce ISA specific SMM entry/exit callbacks

[Ladi Prosek <lprosek@redhat.com>]

Entering and exiting SMM may require ISA specific handling under certain
circumstances. This commit adds two new callbacks with empty implementations.
Actual functionality will be added in following commits.

* prep_enter_smm() is to be called when injecting an SMM, before any
  SMM related vcpu state has been changed
* post_leave_smm() is to be called when emulating the RSM instruction,
  after all SMM related vcpu state has been restored

Signed-off-by: Ladi Prosek <lprosek@redhat.com>
---
 arch/x86/include/asm/kvm_emulate.h |  2 ++
 arch/x86/include/asm/kvm_host.h    |  3 +++
 arch/x86/kvm/svm.c                 | 15 +++++++++++++++
 arch/x86/kvm/vmx.c                 | 15 +++++++++++++++
 arch/x86/kvm/x86.c                 | 13 ++++++++++++-
 5 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index fa2558e12024..99f83367b92c 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -289,6 +289,7 @@ struct x86_emulate_ctxt {
 	/* Register state before/after emulation. */
 	unsigned long eflags;
 	unsigned long eip; /* eip before instruction emulation */
+	u64 smbase; /* smbase before instruction emulation */
 	/* Emulated execution mode, represented by an X86EMUL_MODE value. */
 	enum x86emul_mode mode;
 
@@ -298,6 +299,7 @@ struct x86_emulate_ctxt {
 	bool perm_ok; /* do not check permissions if true */
 	bool ud;	/* inject an #UD if host doesn't support insn */
 	bool tf;	/* TF value before instruction (after for syscall/sysret) */
+	bool left_smm;  /* post_leave_smm() needs to be called after emulation */
 
 	bool have_exception;
 	struct x86_exception exception;
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c73e493adf07..596f2e826327 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1061,6 +1061,9 @@ struct kvm_x86_ops {
 	void (*cancel_hv_timer)(struct kvm_vcpu *vcpu);
 
 	void (*setup_mce)(struct kvm_vcpu *vcpu);
+
+	int (*prep_enter_smm)(struct kvm_vcpu *vcpu, char *smstate);
+	int (*post_leave_smm)(struct kvm_vcpu *vcpu, u64 smbase);
 };
 
 struct kvm_arch_async_pf {
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 0e68f0b3cbf7..cdbbf9537111 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5393,6 +5393,18 @@ static void svm_setup_mce(struct kvm_vcpu *vcpu)
 	vcpu->arch.mcg_cap &= 0x1ff;
 }
 
+static int svm_prep_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
+{
+	/* TODO: Implement */
+	return 0;
+}
+
+static int svm_post_leave_smm(struct kvm_vcpu *vcpu, u64 smbase)
+{
+	/* TODO: Implement */
+	return 0;
+}
+
 static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
 	.cpu_has_kvm_support = has_svm,
 	.disabled_by_bios = is_disabled,
@@ -5503,6 +5515,9 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
 	.deliver_posted_interrupt = svm_deliver_avic_intr,
 	.update_pi_irte = svm_update_pi_irte,
 	.setup_mce = svm_setup_mce,
+
+	.prep_enter_smm = svm_prep_enter_smm,
+	.post_leave_smm = svm_post_leave_smm,
 };
 
 static int __init svm_init(void)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c83d28b0ab05..10f5526f1069 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -11946,6 +11946,18 @@ static void vmx_setup_mce(struct kvm_vcpu *vcpu)
 			~FEATURE_CONTROL_LMCE;
 }
 
+static int vmx_prep_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
+{
+	/* TODO: Implement */
+	return 0;
+}
+
+static int vmx_post_leave_smm(struct kvm_vcpu *vcpu, u64 smbase)
+{
+	/* TODO: Implement */
+	return 0;
+}
+
 static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
 	.cpu_has_kvm_support = cpu_has_kvm_support,
 	.disabled_by_bios = vmx_disabled_by_bios,
@@ -12071,6 +12083,9 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
 #endif
 
 	.setup_mce = vmx_setup_mce,
+
+	.prep_enter_smm = vmx_prep_enter_smm,
+	.post_leave_smm = vmx_post_leave_smm,
 };
 
 static int __init vmx_init(void)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index cd17b7d9a107..8007a6ec2e5b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5272,7 +5272,11 @@ static unsigned emulator_get_hflags(struct x86_emulate_ctxt *ctxt)
 
 static void emulator_set_hflags(struct x86_emulate_ctxt *ctxt, unsigned emul_flags)
 {
-	kvm_set_hflags(emul_to_vcpu(ctxt), emul_flags);
+	struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
+
+	if ((vcpu->arch.hflags & HF_SMM_MASK) && !(emul_flags & HF_SMM_MASK))
+		ctxt->left_smm = true;
+	kvm_set_hflags(vcpu, emul_flags);
 }
 
 static const struct x86_emulate_ops emulate_ops = {
@@ -5692,6 +5696,8 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
 		ctxt->have_exception = false;
 		ctxt->exception.vector = -1;
 		ctxt->perm_ok = false;
+		ctxt->smbase = ctxt->ops->get_smbase(ctxt);
+		ctxt->left_smm = false;
 
 		ctxt->ud = emulation_type & EMULTYPE_TRAP_UD;
 
@@ -5779,6 +5785,8 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
 		if (!ctxt->have_exception ||
 		    exception_type(ctxt->exception.vector) == EXCPT_TRAP)
 			__kvm_set_rflags(vcpu, ctxt->eflags);
+		if (r == EMULATE_DONE && ctxt->left_smm)
+			kvm_x86_ops->post_leave_smm(vcpu, ctxt->smbase);
 
 		/*
 		 * For STI, interrupts are shadowed; so KVM_REQ_EVENT will
@@ -6643,6 +6651,9 @@ static void enter_smm(struct kvm_vcpu *vcpu)
 	trace_kvm_enter_smm(vcpu->vcpu_id, vcpu->arch.smbase, true);
 	vcpu->arch.hflags |= HF_SMM_MASK;
 	memset(buf, 0, 512);
+
+	kvm_x86_ops->prep_enter_smm(vcpu, buf);
+
 	if (guest_cpuid_has(vcpu, X86_FEATURE_LM))
 		enter_smm_save_state_64(vcpu, buf);
 	else
-- 
2.13.5