Re: [PATCH v19 096/130] KVM: VMX: Move NMI/exception handler to common helper

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On 2/26/2024 4:26 PM, isaku.yamahata@xxxxxxxxx wrote:
From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>

TDX mostly handles NMI/exception exit mostly the same to VMX case.  The
difference is how to retrieve exit qualification.  To share the code with
TDX, move NMI/exception to a common header, common.h.

Suggest to add "No functional change intended." in the changelog.


Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
  arch/x86/kvm/vmx/common.h | 59 +++++++++++++++++++++++++++++++++
  arch/x86/kvm/vmx/vmx.c    | 68 +++++----------------------------------
  2 files changed, 67 insertions(+), 60 deletions(-)

diff --git a/arch/x86/kvm/vmx/common.h b/arch/x86/kvm/vmx/common.h
index 6f21d0d48809..632af7a76d0a 100644
--- a/arch/x86/kvm/vmx/common.h
+++ b/arch/x86/kvm/vmx/common.h
@@ -4,8 +4,67 @@
#include <linux/kvm_host.h> +#include <asm/traps.h>
+
  #include "posted_intr.h"
  #include "mmu.h"
+#include "vmcs.h"
+#include "x86.h"
+
+extern unsigned long vmx_host_idt_base;
+void vmx_do_interrupt_irqoff(unsigned long entry);
+void vmx_do_nmi_irqoff(void);
+
+static inline void vmx_handle_nm_fault_irqoff(struct kvm_vcpu *vcpu)
+{
+	/*
+	 * Save xfd_err to guest_fpu before interrupt is enabled, so the
+	 * MSR value is not clobbered by the host activity before the guest
+	 * has chance to consume it.
+	 *
+	 * Do not blindly read xfd_err here, since this exception might
+	 * be caused by L1 interception on a platform which doesn't
+	 * support xfd at all.
+	 *
+	 * Do it conditionally upon guest_fpu::xfd. xfd_err matters
+	 * only when xfd contains a non-zero value.
+	 *
+	 * Queuing exception is done in vmx_handle_exit. See comment there.
+	 */
+	if (vcpu->arch.guest_fpu.fpstate->xfd)
+		rdmsrl(MSR_IA32_XFD_ERR, vcpu->arch.guest_fpu.xfd_err);
+}
+
+static inline void vmx_handle_exception_irqoff(struct kvm_vcpu *vcpu,
+					       u32 intr_info)
+{
+	/* if exit due to PF check for async PF */
+	if (is_page_fault(intr_info))
+		vcpu->arch.apf.host_apf_flags = kvm_read_and_reset_apf_flags();
+	/* if exit due to NM, handle before interrupts are enabled */
+	else if (is_nm_fault(intr_info))
+		vmx_handle_nm_fault_irqoff(vcpu);
+	/* Handle machine checks before interrupts are enabled */
+	else if (is_machine_check(intr_info))
+		kvm_machine_check();
+}
+
+static inline void vmx_handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu,
+							u32 intr_info)
+{
+	unsigned int vector = intr_info & INTR_INFO_VECTOR_MASK;
+	gate_desc *desc = (gate_desc *)vmx_host_idt_base + vector;
+
+	if (KVM_BUG(!is_external_intr(intr_info), vcpu->kvm,
+	    "unexpected VM-Exit interrupt info: 0x%x", intr_info))
+		return;
+
+	kvm_before_interrupt(vcpu, KVM_HANDLING_IRQ);
+	vmx_do_interrupt_irqoff(gate_offset(desc));
+	kvm_after_interrupt(vcpu);
+
+	vcpu->arch.at_instruction_boundary = true;
+}
static inline int __vmx_handle_ept_violation(struct kvm_vcpu *vcpu, gpa_t gpa,
  					     unsigned long exit_qualification)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 29d891e0795e..f8a00a766c40 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -518,7 +518,7 @@ static inline void vmx_segment_cache_clear(struct vcpu_vmx *vmx)
  	vmx->segment_cache.bitmask = 0;
  }
-static unsigned long host_idt_base;
+unsigned long vmx_host_idt_base;
#if IS_ENABLED(CONFIG_HYPERV)
  static bool __read_mostly enlightened_vmcs = true;
@@ -4273,7 +4273,7 @@ void vmx_set_constant_host_state(struct vcpu_vmx *vmx)
  	vmcs_write16(HOST_SS_SELECTOR, __KERNEL_DS);  /* 22.2.4 */
  	vmcs_write16(HOST_TR_SELECTOR, GDT_ENTRY_TSS*8);  /* 22.2.4 */
- vmcs_writel(HOST_IDTR_BASE, host_idt_base); /* 22.2.4 */
+	vmcs_writel(HOST_IDTR_BASE, vmx_host_idt_base);   /* 22.2.4 */
vmcs_writel(HOST_RIP, (unsigned long)vmx_vmexit); /* 22.2.5 */ @@ -5166,7 +5166,7 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
  	intr_info = vmx_get_intr_info(vcpu);
/*
-	 * Machine checks are handled by handle_exception_irqoff(), or by
+	 * Machine checks are handled by vmx_handle_exception_irqoff(), or by
  	 * vmx_vcpu_run() if a #MC occurs on VM-Entry.  NMIs are handled by
  	 * vmx_vcpu_enter_exit().
  	 */
@@ -5174,7 +5174,7 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
  		return 1;
/*
-	 * Queue the exception here instead of in handle_nm_fault_irqoff().
+	 * Queue the exception here instead of in vmx_handle_nm_fault_irqoff().
  	 * This ensures the nested_vmx check is not skipped so vmexit can
  	 * be reflected to L1 (when it intercepts #NM) before reaching this
  	 * point.
@@ -6889,59 +6889,6 @@ void vmx_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)
  	vmcs_write64(EOI_EXIT_BITMAP3, eoi_exit_bitmap[3]);
  }
-void vmx_do_interrupt_irqoff(unsigned long entry);
-void vmx_do_nmi_irqoff(void);
-
-static void handle_nm_fault_irqoff(struct kvm_vcpu *vcpu)
-{
-	/*
-	 * Save xfd_err to guest_fpu before interrupt is enabled, so the
-	 * MSR value is not clobbered by the host activity before the guest
-	 * has chance to consume it.
-	 *
-	 * Do not blindly read xfd_err here, since this exception might
-	 * be caused by L1 interception on a platform which doesn't
-	 * support xfd at all.
-	 *
-	 * Do it conditionally upon guest_fpu::xfd. xfd_err matters
-	 * only when xfd contains a non-zero value.
-	 *
-	 * Queuing exception is done in vmx_handle_exit. See comment there.
-	 */
-	if (vcpu->arch.guest_fpu.fpstate->xfd)
-		rdmsrl(MSR_IA32_XFD_ERR, vcpu->arch.guest_fpu.xfd_err);
-}
-
-static void handle_exception_irqoff(struct kvm_vcpu *vcpu, u32 intr_info)
-{
-	/* if exit due to PF check for async PF */
-	if (is_page_fault(intr_info))
-		vcpu->arch.apf.host_apf_flags = kvm_read_and_reset_apf_flags();
-	/* if exit due to NM, handle before interrupts are enabled */
-	else if (is_nm_fault(intr_info))
-		handle_nm_fault_irqoff(vcpu);
-	/* Handle machine checks before interrupts are enabled */
-	else if (is_machine_check(intr_info))
-		kvm_machine_check();
-}
-
-static void handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu,
-					     u32 intr_info)
-{
-	unsigned int vector = intr_info & INTR_INFO_VECTOR_MASK;
-	gate_desc *desc = (gate_desc *)host_idt_base + vector;
-
-	if (KVM_BUG(!is_external_intr(intr_info), vcpu->kvm,
-	    "unexpected VM-Exit interrupt info: 0x%x", intr_info))
-		return;
-
-	kvm_before_interrupt(vcpu, KVM_HANDLING_IRQ);
-	vmx_do_interrupt_irqoff(gate_offset(desc));
-	kvm_after_interrupt(vcpu);
-
-	vcpu->arch.at_instruction_boundary = true;
-}
-
  void vmx_handle_exit_irqoff(struct kvm_vcpu *vcpu)
  {
  	struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -6950,9 +6897,10 @@ void vmx_handle_exit_irqoff(struct kvm_vcpu *vcpu)
  		return;
if (vmx->exit_reason.basic == EXIT_REASON_EXTERNAL_INTERRUPT)
-		handle_external_interrupt_irqoff(vcpu, vmx_get_intr_info(vcpu));
+		vmx_handle_external_interrupt_irqoff(vcpu,
+						     vmx_get_intr_info(vcpu));
  	else if (vmx->exit_reason.basic == EXIT_REASON_EXCEPTION_NMI)
-		handle_exception_irqoff(vcpu, vmx_get_intr_info(vcpu));
+		vmx_handle_exception_irqoff(vcpu, vmx_get_intr_info(vcpu));
  }
/*
@@ -8284,7 +8232,7 @@ __init int vmx_hardware_setup(void)
  	int r;
store_idt(&dt);
-	host_idt_base = dt.address;
+	vmx_host_idt_base = dt.address;
vmx_setup_user_return_msrs();





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