FAILED: patch "[PATCH] KVM: nVMX: Add a helper to get highest pending from Posted" failed to apply to 6.1-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x d83c36d822be44db4bad0c43bea99c8908f54117
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024072948-cosponsor-jacket-16bb@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

d83c36d822be ("KVM: nVMX: Add a helper to get highest pending from Posted Interrupt vector")
699f67512f04 ("KVM: VMX: Move posted interrupt descriptor out of VMX code")
50a82b0eb88c ("KVM: VMX: Split off vmx_onhyperv.{ch} from hyperv.{ch}")
662f6815786e ("KVM: VMX: Rename XSAVES control to follow KVM's preferred "ENABLE_XYZ"")
1143c0b85c07 ("KVM: VMX: Recompute "XSAVES enabled" only after CPUID update")
fbc722aac1ce ("KVM: VMX: Rename "KVM is using eVMCS" static key to match its wrapper")
19f10315fd53 ("KVM: VMX: Stub out enable_evmcs static key for CONFIG_HYPERV=n")
68ac4221497b ("KVM: nVMX: Move EVMCS1_SUPPORT_* macros to hyperv.c")
93827a0a3639 ("KVM: VMX: Fix crash due to uninitialized current_vmcs")
11633f69506d ("KVM: VMX: Always inline eVMCS read/write helpers")
d83420c2d74e ("KVM: x86: Move CPU compat checks hook to kvm_x86_ops (from kvm_x86_init_ops)")
325fc9579c2e ("KVM: SVM: Check for SVM support in CPU compatibility checks")
8504ef2139e2 ("KVM: VMX: Shuffle support checks and hardware enabling code around")
d41931324975 ("KVM: x86: Do VMX/SVM support checks directly in vendor code")
462689b37f08 ("KVM: VMX: Use current CPU's info to perform "disabled by BIOS?" checks")
8d20bd638167 ("KVM: x86: Unify pr_fmt to use module name for all KVM modules")
3045c483eeee ("KVM: x86: Do CPU compatibility checks in x86 code")
a578a0a9e352 ("KVM: Drop kvm_arch_{init,exit}() hooks")
20deee32f553 ("KVM: RISC-V: Do arch init directly in riscv_kvm_init()")
3fb8e89aa2a0 ("KVM: MIPS: Setup VZ emulation? directly from kvm_mips_init()")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d83c36d822be44db4bad0c43bea99c8908f54117 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@google.com>
Date: Fri, 7 Jun 2024 10:26:04 -0700
Subject: [PATCH] KVM: nVMX: Add a helper to get highest pending from Posted
 Interrupt vector

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>

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 643935a0f70a..8f4db6e8f57c 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 */