6.10-stable review patch. If anyone has any objections, please let me know.
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From: Sean Christopherson seanjc@google.com
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 --- arch/x86/kvm/vmx/nested.c | 5 +++-- arch/x86/kvm/vmx/posted_intr.h | 10 ++++++++++ 2 files changed, 13 insertions(+), 2 deletions(-)
--- 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_in 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; --- 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, 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 */