diff mbox series

KVM: selftests: Add helpers for locally (un)blocking IRQs on x86

Message ID 20241220012617.3513898-1-seanjc@google.com (mailing list archive)
State New
Headers show
Series KVM: selftests: Add helpers for locally (un)blocking IRQs on x86 | expand

Commit Message

Sean Christopherson Dec. 20, 2024, 1:26 a.m. UTC 
Copy KVM-Unit-Tests' x86 helpers for emitting STI and CLI, comments and
all, and use them throughout x86 selftests.  The safe_halt() and sti_nop()
logic in particular benefits from centralized comments, as the behavior
isn't obvious unless the reader is already aware of the STI shadow.

Cc: Manali Shukla <Manali.Shukla@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 .../selftests/kvm/include/x86/processor.h     | 40 +++++++++++++++++++
 tools/testing/selftests/kvm/x86/hyperv_ipi.c  |  6 ++-
 .../selftests/kvm/x86/svm_int_ctl_test.c      |  5 +--
 .../selftests/kvm/x86/ucna_injection_test.c   |  2 +-
 .../selftests/kvm/x86/xapic_ipi_test.c        |  3 +-
 .../selftests/kvm/x86/xapic_state_test.c      |  4 +-
 .../selftests/kvm/x86/xen_shinfo_test.c       |  5 +--
 7 files changed, 51 insertions(+), 14 deletions(-)


base-commit: dcab55cef6f247a71a75a239d4063018dc83a671
diff mbox series

Patch

diff --git a/tools/testing/selftests/kvm/include/x86/processor.h b/tools/testing/selftests/kvm/include/x86/processor.h
index d60da8966772..1f9798ed71f1 100644
--- a/tools/testing/selftests/kvm/include/x86/processor.h
+++ b/tools/testing/selftests/kvm/include/x86/processor.h
@@ -1339,6 +1339,46 @@  static inline void kvm_hypercall_map_gpa_range(uint64_t gpa, uint64_t size,
 	GUEST_ASSERT(!ret);
 }
 
+/*
+ * Execute HLT in an STI interrupt shadow to ensure that a pending IRQ that's
+ * intended to be a wake event arrives *after* HLT is executed.  Modern CPUs,
+ * except for a few oddballs that KVM is unlikely to run on, block IRQs for one
+ * instruction after STI, *if* RFLAGS.IF=0 before STI.  Note, Intel CPUs may
+ * block other events beyond regular IRQs, e.g. may block NMIs and SMIs too.
+ */
+static inline void safe_halt(void)
+{
+	asm volatile("sti; hlt");
+}
+
+/*
+ * Enable interrupts and ensure that interrupts are evaluated upon return from
+ * this function, i.e. execute a nop to consume the STi interrupt shadow.
+ */
+static inline void sti_nop(void)
+{
+	asm volatile ("sti; nop");
+}
+
+/*
+ * Enable interrupts for one instruction (nop), to allow the CPU to process all
+ * interrupts that are already pending.
+ */
+static inline void sti_nop_cli(void)
+{
+	asm volatile ("sti; nop; cli");
+}
+
+static inline void sti(void)
+{
+	asm volatile("sti");
+}
+
+static inline void cli(void)
+{
+	asm volatile ("cli");
+}
+
 void __vm_xsave_require_permission(uint64_t xfeature, const char *name);
 
 #define vm_xsave_require_permission(xfeature)	\
diff --git a/tools/testing/selftests/kvm/x86/hyperv_ipi.c b/tools/testing/selftests/kvm/x86/hyperv_ipi.c
index 22c0c124582f..2b5b4bc6ef7e 100644
--- a/tools/testing/selftests/kvm/x86/hyperv_ipi.c
+++ b/tools/testing/selftests/kvm/x86/hyperv_ipi.c
@@ -63,8 +63,10 @@  static void receiver_code(void *hcall_page, vm_vaddr_t pgs_gpa)
 	/* Signal sender vCPU we're ready */
 	ipis_rcvd[vcpu_id] = (u64)-1;
 
-	for (;;)
-		asm volatile("sti; hlt; cli");
+	for (;;) {
+		safe_halt();
+		cli();
+	}
 }
 
 static void guest_ipi_handler(struct ex_regs *regs)
diff --git a/tools/testing/selftests/kvm/x86/svm_int_ctl_test.c b/tools/testing/selftests/kvm/x86/svm_int_ctl_test.c
index 916e04248fbb..917b6066cfc1 100644
--- a/tools/testing/selftests/kvm/x86/svm_int_ctl_test.c
+++ b/tools/testing/selftests/kvm/x86/svm_int_ctl_test.c
@@ -42,10 +42,7 @@  static void l2_guest_code(struct svm_test_data *svm)
 	x2apic_write_reg(APIC_ICR,
 		APIC_DEST_SELF | APIC_INT_ASSERT | INTR_IRQ_NUMBER);
 
-	__asm__ __volatile__(
-		"sti\n"
-		"nop\n"
-	);
+	sti_nop();
 
 	GUEST_ASSERT(vintr_irq_called);
 	GUEST_ASSERT(intr_irq_called);
diff --git a/tools/testing/selftests/kvm/x86/ucna_injection_test.c b/tools/testing/selftests/kvm/x86/ucna_injection_test.c
index 57f157c06b39..1e5e564523b3 100644
--- a/tools/testing/selftests/kvm/x86/ucna_injection_test.c
+++ b/tools/testing/selftests/kvm/x86/ucna_injection_test.c
@@ -86,7 +86,7 @@  static void ucna_injection_guest_code(void)
 	wrmsr(MSR_IA32_MCx_CTL2(UCNA_BANK), ctl2 | MCI_CTL2_CMCI_EN);
 
 	/* Enables interrupt in guest. */
-	asm volatile("sti");
+	sti();
 
 	/* Let user space inject the first UCNA */
 	GUEST_SYNC(SYNC_FIRST_UCNA);
diff --git a/tools/testing/selftests/kvm/x86/xapic_ipi_test.c b/tools/testing/selftests/kvm/x86/xapic_ipi_test.c
index a76078a08ff8..6228c0806e89 100644
--- a/tools/testing/selftests/kvm/x86/xapic_ipi_test.c
+++ b/tools/testing/selftests/kvm/x86/xapic_ipi_test.c
@@ -106,7 +106,8 @@  static void halter_guest_code(struct test_data_page *data)
 		data->halter_tpr = xapic_read_reg(APIC_TASKPRI);
 		data->halter_ppr = xapic_read_reg(APIC_PROCPRI);
 		data->hlt_count++;
-		asm volatile("sti; hlt; cli");
+		safe_halt();
+		cli();
 		data->wake_count++;
 	}
 }
diff --git a/tools/testing/selftests/kvm/x86/xapic_state_test.c b/tools/testing/selftests/kvm/x86/xapic_state_test.c
index 88bcca188799..fdebff1165c7 100644
--- a/tools/testing/selftests/kvm/x86/xapic_state_test.c
+++ b/tools/testing/selftests/kvm/x86/xapic_state_test.c
@@ -18,7 +18,7 @@  struct xapic_vcpu {
 
 static void xapic_guest_code(void)
 {
-	asm volatile("cli");
+	cli();
 
 	xapic_enable();
 
@@ -38,7 +38,7 @@  static void xapic_guest_code(void)
 
 static void x2apic_guest_code(void)
 {
-	asm volatile("cli");
+	cli();
 
 	x2apic_enable();
 
diff --git a/tools/testing/selftests/kvm/x86/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86/xen_shinfo_test.c
index a59b3c799bb2..287829f850f7 100644
--- a/tools/testing/selftests/kvm/x86/xen_shinfo_test.c
+++ b/tools/testing/selftests/kvm/x86/xen_shinfo_test.c
@@ -191,10 +191,7 @@  static void guest_code(void)
 	struct vcpu_runstate_info *rs = (void *)RUNSTATE_VADDR;
 	int i;
 
-	__asm__ __volatile__(
-		"sti\n"
-		"nop\n"
-	);
+	sti_nop();
 
 	/* Trigger an interrupt injection */
 	GUEST_SYNC(TEST_INJECT_VECTOR);