[PATCH v7 01/10] x86/fred: Provide separate IRQ vs. NMI wrappers for entry from KVM
From: Sohil Mehta <hidden>
Date: 2025-06-12 21:50:28
Also in:
kvm, linux-edac, linux-perf-users, linux-pm, lkml
Subsystem:
intel(r) flexible return and event delivery, kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Xin Li, "H. Peter Anvin", Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Sean Christopherson <seanjc@google.com> Provide separate wrappers for forwarding IRQs vs NMIs from KVM in anticipation of adding support for NMI source reporting, which will add an NMI-only parameter, i.e. will further pollute the current API with a param that is a hardcoded for one of the two call sites. Opportunistically tag the non-FRED NMI wrapper __always_inline, as the compiler could theoretically generate a function call and trigger and a (completely benign) "leaving noinstr" warning. Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Sohil Mehta <redacted> --- v7: New patch --- arch/x86/include/asm/fred.h | 30 ++++++++++++++++++++++-------- arch/x86/kvm/vmx/vmx.c | 4 ++-- 2 files changed, 24 insertions(+), 10 deletions(-)
diff --git a/arch/x86/include/asm/fred.h b/arch/x86/include/asm/fred.h
index 12b34d5b2953..552332ca060c 100644
--- a/arch/x86/include/asm/fred.h
+++ b/arch/x86/include/asm/fred.h@@ -9,6 +9,7 @@ #include <linux/const.h> #include <asm/asm.h> +#include <asm/irq_vectors.h> #include <asm/msr.h> #include <asm/trapnr.h>
@@ -71,15 +72,27 @@ __visible void fred_entry_from_user(struct pt_regs *regs); __visible void fred_entry_from_kernel(struct pt_regs *regs); __visible void __fred_entry_from_kvm(struct pt_regs *regs); -/* Can be called from noinstr code, thus __always_inline */ -static __always_inline void fred_entry_from_kvm(unsigned int type, unsigned int vector) +/* Must be called from noinstr code, thus __always_inline */ +static __always_inline void fred_nmi_from_kvm(void) { struct fred_ss ss = { - .ss =__KERNEL_DS, - .type = type, - .vector = vector, - .nmi = type == EVENT_TYPE_NMI, - .lm = 1, + .ss = __KERNEL_DS, + .type = EVENT_TYPE_NMI, + .vector = NMI_VECTOR, + .nmi = true, + .lm = 1, + }; + + asm_fred_entry_from_kvm(ss); +} + +static inline void fred_irq_from_kvm(unsigned int vector) +{ + struct fred_ss ss = { + .ss = __KERNEL_DS, + .type = EVENT_TYPE_EXTINT, + .vector = vector, + .lm = 1, }; asm_fred_entry_from_kvm(ss);
@@ -110,7 +123,8 @@ static __always_inline unsigned long fred_event_data(struct pt_regs *regs) { ret static inline void cpu_init_fred_exceptions(void) { } static inline void cpu_init_fred_rsps(void) { } static inline void fred_complete_exception_setup(void) { } -static inline void fred_entry_from_kvm(unsigned int type, unsigned int vector) { } +static __always_inline void fred_nmi_from_kvm(void) { } +static inline void fred_irq_from_kvm(unsigned int vector) { } static inline void fred_sync_rsp0(unsigned long rsp0) { } static inline void fred_update_rsp0(void) { } #endif /* CONFIG_X86_FRED */
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4953846cb30d..8183886eda3d 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c@@ -6991,7 +6991,7 @@ static void handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu, kvm_before_interrupt(vcpu, KVM_HANDLING_IRQ); if (cpu_feature_enabled(X86_FEATURE_FRED)) - fred_entry_from_kvm(EVENT_TYPE_EXTINT, vector); + fred_irq_from_kvm(vector); else vmx_do_interrupt_irqoff(gate_offset((gate_desc *)host_idt_base + vector)); kvm_after_interrupt(vcpu);
@@ -7264,7 +7264,7 @@ noinstr void vmx_handle_nmi(struct kvm_vcpu *vcpu) kvm_before_interrupt(vcpu, KVM_HANDLING_NMI); if (cpu_feature_enabled(X86_FEATURE_FRED)) - fred_entry_from_kvm(EVENT_TYPE_NMI, NMI_VECTOR); + fred_nmi_from_kvm(); else vmx_do_nmi_irqoff(); kvm_after_interrupt(vcpu);
--
2.43.0