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KVM: nVMX: Add a helper to get highest pending from Posted Interrupt vector

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commit d83c36d822be44db4bad0c43bea99c8908f54117 upstream.

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@vger.kernel.org
Link: https://lore.kernel.org/r/20240607172609.3205077-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sean Christopherson 2024-06-07 10:26:04 -07:00 committed by Greg Kroah-Hartman
parent a8ab69cf6f
commit 0c6c9421b0
2 changed files with 13 additions and 2 deletions
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5
arch/x86/kvm/vmx/nested.c
View File

@ -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;

10
arch/x86/kvm/vmx/posted_intr.h
View File

@ -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 */