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From: isaku.yamahata@intel.com
To: kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: isaku.yamahata@intel.com,
	isaku.yamahata@gmail.com,
	Paolo Bonzini <pbonzini@redhat.com>,
	erdemaktas@google.com,
	Sean Christopherson <seanjc@google.com>,
	Sagi Shahar <sagis@google.com>,
	Kai Huang <kai.huang@intel.com>,
	chen.bo@intel.com,
	hang.yuan@intel.com,
	tina.zhang@intel.com
Subject: [PATCH v18 100/121] KVM: TDX: Implement callbacks for MSR operations for TDX
Date: Mon, 22 Jan 2024 15:54:16 -0800
Message-Id: <01cc1936f68d98010c077a83d8d6ea001df82c57.1705965635.git.isaku.yamahata@intel.com>
In-Reply-To: <cover.1705965634.git.isaku.yamahata@intel.com>
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From: Isaku Yamahata <isaku.yamahata@intel.com>

Implements set_msr/get_msr/has_emulated_msr methods for TDX to handle
hypercall from guest TD for paravirtualized rdmsr and wrmsr.  The TDX
module virtualizes MSRs.  For some MSRs, it injects #VE to the guest TD
upon RDMSR or WRMSR.  The exact list of such MSRs are defined in the spec.

Upon #VE, the guest TD may execute hypercalls,
TDG.VP.VMCALL<INSTRUCTION.RDMSR> and TDG.VP.VMCALL<INSTRUCTION.WRMSR>,
which are defined in GHCI (Guest-Host Communication Interface) so that the
host VMM (e.g. KVM) can virtualize the MSRs.

There are three classes of MSRs virtualization.
- non-configurable: TDX module directly virtualizes it. VMM can't
  configure. the value set by KVM_SET_MSR_INDEX_LIST is ignored.
- configurable: TDX module directly virtualizes it. VMM can configure at
  the VM creation time.  The value set by KVM_SET_MSR_INDEX_LIST is used.
- #VE case
  Guest TD would issue TDG.VP.VMCALL<INSTRUCTION.{WRMSR,RDMSR> and
  VMM handles the MSR hypercall. The value set by KVM_SET_MSR_INDEX_LIST
  is used.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/vmx/main.c    | 44 +++++++++++++++++++++---
 arch/x86/kvm/vmx/tdx.c     | 70 ++++++++++++++++++++++++++++++++++++++
 arch/x86/kvm/vmx/x86_ops.h |  6 ++++
 arch/x86/kvm/x86.c         |  1 -
 arch/x86/kvm/x86.h         |  2 ++
 5 files changed, 118 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index 1a20542f3a84..0373744ecf00 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -262,6 +262,42 @@ static void vt_handle_exit_irqoff(struct kvm_vcpu *vcpu)
 	vmx_handle_exit_irqoff(vcpu);
 }
 
+static int vt_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
+{
+	if (unlikely(is_td_vcpu(vcpu)))
+		return tdx_set_msr(vcpu, msr_info);
+
+	return vmx_set_msr(vcpu, msr_info);
+}
+
+/*
+ * The kvm parameter can be NULL (module initialization, or invocation before
+ * VM creation). Be sure to check the kvm parameter before using it.
+ */
+static bool vt_has_emulated_msr(struct kvm *kvm, u32 index)
+{
+	if (kvm && is_td(kvm))
+		return tdx_has_emulated_msr(index, true);
+
+	return vmx_has_emulated_msr(kvm, index);
+}
+
+static int vt_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
+{
+	if (unlikely(is_td_vcpu(vcpu)))
+		return tdx_get_msr(vcpu, msr_info);
+
+	return vmx_get_msr(vcpu, msr_info);
+}
+
+static void vt_msr_filter_changed(struct kvm_vcpu *vcpu)
+{
+	if (is_td_vcpu(vcpu))
+		return;
+
+	vmx_msr_filter_changed(vcpu);
+}
+
 static void vt_apicv_pre_state_restore(struct kvm_vcpu *vcpu)
 {
 	struct pi_desc *pi = vcpu_to_pi_desc(vcpu);
@@ -523,7 +559,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 
 	.hardware_enable = vt_hardware_enable,
 	.hardware_disable = vt_hardware_disable,
-	.has_emulated_msr = vmx_has_emulated_msr,
+	.has_emulated_msr = vt_has_emulated_msr,
 
 	.is_vm_type_supported = vt_is_vm_type_supported,
 	.max_vcpus = vt_max_vcpus,
@@ -545,8 +581,8 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 
 	.update_exception_bitmap = vmx_update_exception_bitmap,
 	.get_msr_feature = vmx_get_msr_feature,
-	.get_msr = vmx_get_msr,
-	.set_msr = vmx_set_msr,
+	.get_msr = vt_get_msr,
+	.set_msr = vt_set_msr,
 	.get_segment_base = vmx_get_segment_base,
 	.get_segment = vmx_get_segment,
 	.set_segment = vmx_set_segment,
@@ -656,7 +692,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 	.apic_init_signal_blocked = vmx_apic_init_signal_blocked,
 	.migrate_timers = vmx_migrate_timers,
 
-	.msr_filter_changed = vmx_msr_filter_changed,
+	.msr_filter_changed = vt_msr_filter_changed,
 	.complete_emulated_msr = kvm_complete_insn_gp,
 
 	.vcpu_deliver_sipi_vector = kvm_vcpu_deliver_sipi_vector,
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index bca1267b89bd..396dd540f2d5 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1923,6 +1923,76 @@ void tdx_get_exit_info(struct kvm_vcpu *vcpu, u32 *reason,
 	*error_code = 0;
 }
 
+static bool tdx_is_emulated_kvm_msr(u32 index, bool write)
+{
+	switch (index) {
+	case MSR_KVM_POLL_CONTROL:
+		return true;
+	default:
+		return false;
+	}
+}
+
+bool tdx_has_emulated_msr(u32 index, bool write)
+{
+	switch (index) {
+	case MSR_IA32_UCODE_REV:
+	case MSR_IA32_ARCH_CAPABILITIES:
+	case MSR_IA32_POWER_CTL:
+	case MSR_IA32_CR_PAT:
+	case MSR_IA32_TSC_DEADLINE:
+	case MSR_IA32_MISC_ENABLE:
+	case MSR_PLATFORM_INFO:
+	case MSR_MISC_FEATURES_ENABLES:
+	case MSR_IA32_MCG_CAP:
+	case MSR_IA32_MCG_STATUS:
+	case MSR_IA32_MCG_CTL:
+	case MSR_IA32_MCG_EXT_CTL:
+	case MSR_IA32_MC0_CTL ... MSR_IA32_MCx_CTL(KVM_MAX_MCE_BANKS) - 1:
+	case MSR_IA32_MC0_CTL2 ... MSR_IA32_MCx_CTL2(KVM_MAX_MCE_BANKS) - 1:
+		/* MSR_IA32_MCx_{CTL, STATUS, ADDR, MISC, CTL2} */
+		return true;
+	case APIC_BASE_MSR ... APIC_BASE_MSR + 0xff:
+		/*
+		 * x2APIC registers that are virtualized by the CPU can't be
+		 * emulated, KVM doesn't have access to the virtual APIC page.
+		 */
+		switch (index) {
+		case X2APIC_MSR(APIC_TASKPRI):
+		case X2APIC_MSR(APIC_PROCPRI):
+		case X2APIC_MSR(APIC_EOI):
+		case X2APIC_MSR(APIC_ISR) ... X2APIC_MSR(APIC_ISR + APIC_ISR_NR):
+		case X2APIC_MSR(APIC_TMR) ... X2APIC_MSR(APIC_TMR + APIC_ISR_NR):
+		case X2APIC_MSR(APIC_IRR) ... X2APIC_MSR(APIC_IRR + APIC_ISR_NR):
+			return false;
+		default:
+			return true;
+		}
+	case MSR_IA32_APICBASE:
+	case MSR_EFER:
+		return !write;
+	case 0x4b564d00 ... 0x4b564dff:
+		/* KVM custom MSRs */
+		return tdx_is_emulated_kvm_msr(index, write);
+	default:
+		return false;
+	}
+}
+
+int tdx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
+{
+	if (tdx_has_emulated_msr(msr->index, false))
+		return kvm_get_msr_common(vcpu, msr);
+	return 1;
+}
+
+int tdx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
+{
+	if (tdx_has_emulated_msr(msr->index, true))
+		return kvm_set_msr_common(vcpu, msr);
+	return 1;
+}
+
 static int tdx_get_capabilities(struct kvm_tdx_cmd *cmd)
 {
 	struct kvm_tdx_capabilities __user *user_caps;
diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
index 7877debdce8a..608db691b1b8 100644
--- a/arch/x86/kvm/vmx/x86_ops.h
+++ b/arch/x86/kvm/vmx/x86_ops.h
@@ -165,6 +165,9 @@ void tdx_deliver_interrupt(struct kvm_lapic *apic, int delivery_mode,
 void tdx_inject_nmi(struct kvm_vcpu *vcpu);
 void tdx_get_exit_info(struct kvm_vcpu *vcpu, u32 *reason,
 		u64 *info1, u64 *info2, u32 *intr_info, u32 *error_code);
+bool tdx_has_emulated_msr(u32 index, bool write);
+int tdx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr);
+int tdx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr);
 
 int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp);
 
@@ -207,6 +210,9 @@ static inline void tdx_deliver_interrupt(struct kvm_lapic *apic, int delivery_mo
 static inline void tdx_inject_nmi(struct kvm_vcpu *vcpu) {}
 static inline void tdx_get_exit_info(struct kvm_vcpu *vcpu, u32 *reason, u64 *info1,
 				     u64 *info2, u32 *intr_info, u32 *error_code) {}
+static inline bool tdx_has_emulated_msr(u32 index, bool write) { return false; }
+static inline int tdx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) { return 1; }
+static inline int tdx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) { return 1; }
 
 static inline int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp) { return -EOPNOTSUPP; }
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ac934542b086..161e5f41497f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -90,7 +90,6 @@
 #include "trace.h"
 
 #define MAX_IO_MSRS 256
-#define KVM_MAX_MCE_BANKS 32
 
 struct kvm_caps kvm_caps __read_mostly = {
 	.supported_mce_cap = MCG_CTL_P | MCG_SER_P,
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 4e40c23d66ed..c87b7a777b67 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -9,6 +9,8 @@
 #include "kvm_cache_regs.h"
 #include "kvm_emulate.h"
 
+#define KVM_MAX_MCE_BANKS 32
+
 bool __kvm_is_vm_type_supported(unsigned long type);
 
 struct kvm_caps {
-- 
2.25.1