Re: [PATCH 5.10.y] KVM: x86: Reject Hyper-V's SEND_IPI hypercalls if local APIC isn't in-kernel

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: a8de7f100bb5989d9c3627d3a223ee1c863f3b69

WARNING: Author mismatch between patch and upstream commit:
Backport author: Abdelkareem Abdelsaamad<kareemem@amazon.com>
Commit author: Sean Christopherson<seanjc@google.com>

Status in newer kernel trees:
6.13.y | Present (different SHA1: ca29f58ca374)
6.12.y | Present (different SHA1: aca8be4403fb)
6.6.y | Present (different SHA1: 874ff13c73c4)
6.1.y | Present (different SHA1: 5393cf223124)
5.15.y | Present (different SHA1: 8c0bc4fec456)

Note: The patch differs from the upstream commit:
---
1:  a8de7f100bb59 ! 1:  26c34724741d5 KVM: x86: Reject Hyper-V's SEND_IPI hypercalls if local APIC isn't in-kernel
    @@ Metadata
      ## Commit message ##
         KVM: x86: Reject Hyper-V's SEND_IPI hypercalls if local APIC isn't in-kernel
     
    +    commit a8de7f100bb5989d9c3627d3a223ee1c863f3b69 upstream.
    +
         Advertise support for Hyper-V's SEND_IPI and SEND_IPI_EX hypercalls if and
         only if the local API is emulated/virtualized by KVM, and explicitly reject
         said hypercalls if the local APIC is emulated in userspace, i.e. don't rely
    @@ Commit message
         Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
         Link: https://lore.kernel.org/r/20250118003454.2619573-2-seanjc@google.com
         Signed-off-by: Sean Christopherson <seanjc@google.com>
    +    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    +    [Conflict due to
    +    72167a9d7da2 ("KVM: x86: hyper-v: Stop shadowing global 'current_vcpu'
    +    variable")
    +    not in the tree]
    +    Signed-off-by: Abdelkareem Abdelsaamad <kareemem@amazon.com>
     
      ## arch/x86/kvm/hyperv.c ##
    -@@ arch/x86/kvm/hyperv.c: static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
    +@@ arch/x86/kvm/hyperv.c: static u64 kvm_hv_send_ipi(struct kvm_vcpu *current_vcpu, u64 ingpa, u64 outgpa,
      	u32 vector;
      	bool all_cpus;
      
    -+	if (!lapic_in_kernel(vcpu))
    ++	if (!lapic_in_kernel(current_vcpu))
     +		return HV_STATUS_INVALID_HYPERCALL_INPUT;
     +
    - 	if (hc->code == HVCALL_SEND_IPI) {
    - 		if (!hc->fast) {
    - 			if (unlikely(kvm_read_guest(kvm, hc->ingpa, &send_ipi,
    -@@ arch/x86/kvm/hyperv.c: int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,
    + 	if (!ex) {
    + 		if (!fast) {
    + 			if (unlikely(kvm_read_guest(kvm, ingpa, &send_ipi,
    +@@ arch/x86/kvm/hyperv.c: int kvm_vcpu_ioctl_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,
      			ent->eax |= HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED;
      			ent->eax |= HV_X64_APIC_ACCESS_RECOMMENDED;
      			ent->eax |= HV_X64_RELAXED_TIMING_RECOMMENDED;
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.10.y       |  Success    |  Success   |