Add a helper to retrieve the highest pending vector given a Posted
Interrupt descriptor. While the actual operation is straightforward, it's
surprisingly easy to mess up, e.g. if one tries to reuse lapic.c's
find_highest_vector(), which doesn't work with PID.PIR due to the APIC's
IRR and ISR component registers being physically discontiguous (they're
4-byte registers aligned at 16-byte intervals).
To make PIR handling more consistent with respect to IRR and ISR handling,
return -1 to indicate "no interrupt pending".
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/vmx/nested.c | 5 +++--
arch/x86/kvm/vmx/posted_intr.h | 10 ++++++++++
2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 75b4f41d9926..0710486d42cc 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -12,6 +12,7 @@
#include "mmu.h"
#include "nested.h"
#include "pmu.h"
+#include "posted_intr.h"
#include "sgx.h"
#include "trace.h"
#include "vmx.h"
@@ -3899,8 +3900,8 @@ static int vmx_complete_nested_posted_interrupt(struct kvm_vcpu *vcpu)
if (!pi_test_and_clear_on(vmx->nested.pi_desc))
return 0;
- max_irr = find_last_bit((unsigned long *)vmx->nested.pi_desc->pir, 256);
- if (max_irr != 256) {
+ max_irr = pi_find_highest_vector(vmx->nested.pi_desc);
+ if (max_irr > 0) {
vapic_page = vmx->nested.virtual_apic_map.hva;
if (!vapic_page)
goto mmio_needed;
diff --git a/arch/x86/kvm/vmx/posted_intr.h b/arch/x86/kvm/vmx/posted_intr.h
index 6b2a0226257e..1715d2ab07be 100644
--- a/arch/x86/kvm/vmx/posted_intr.h
+++ b/arch/x86/kvm/vmx/posted_intr.h
@@ -1,6 +1,8 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __KVM_X86_VMX_POSTED_INTR_H
#define __KVM_X86_VMX_POSTED_INTR_H
+
+#include <linux/find.h>
#include <asm/posted_intr.h>
void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu);
@@ -12,4 +14,12 @@ int vmx_pi_update_irte(struct kvm *kvm, unsigned int host_irq,
uint32_t guest_irq, bool set);
void vmx_pi_start_assignment(struct kvm *kvm);
+static inline int pi_find_highest_vector(struct pi_desc *pi_desc)
+{
+ int vec;
+
+ vec = find_last_bit((unsigned long *)pi_desc->pir, 256);
+ return vec < 256 ? vec : -1;
+}
+
#endif /* __KVM_X86_VMX_POSTED_INTR_H */
--
2.45.2.505.gda0bf45e8d-goog
