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    Subject[PATCH 5.15 022/779] KVM: SVM: Dont BUG if userspace injects an interrupt with GIF=0
    Date
    From: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>

    commit f17c31c48e5cde9895a491d91c424eeeada3e134 upstream.

    Don't BUG/WARN on interrupt injection due to GIF being cleared,
    since it's trivial for userspace to force the situation via
    KVM_SET_VCPU_EVENTS (even if having at least a WARN there would be correct
    for KVM internally generated injections).

    kernel BUG at arch/x86/kvm/svm/svm.c:3386!
    invalid opcode: 0000 [#1] SMP
    CPU: 15 PID: 926 Comm: smm_test Not tainted 5.17.0-rc3+ #264
    Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
    RIP: 0010:svm_inject_irq+0xab/0xb0 [kvm_amd]
    Code: <0f> 0b 0f 1f 00 0f 1f 44 00 00 80 3d ac b3 01 00 00 55 48 89 f5 53
    RSP: 0018:ffffc90000b37d88 EFLAGS: 00010246
    RAX: 0000000000000000 RBX: ffff88810a234ac0 RCX: 0000000000000006
    RDX: 0000000000000000 RSI: ffffc90000b37df7 RDI: ffff88810a234ac0
    RBP: ffffc90000b37df7 R08: ffff88810a1fa410 R09: 0000000000000000
    R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
    R13: ffff888109571000 R14: ffff88810a234ac0 R15: 0000000000000000
    FS: 0000000001821380(0000) GS:ffff88846fdc0000(0000) knlGS:0000000000000000
    CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 00007f74fc550008 CR3: 000000010a6fe000 CR4: 0000000000350ea0
    Call Trace:
    <TASK>
    inject_pending_event+0x2f7/0x4c0 [kvm]
    kvm_arch_vcpu_ioctl_run+0x791/0x17a0 [kvm]
    kvm_vcpu_ioctl+0x26d/0x650 [kvm]
    __x64_sys_ioctl+0x82/0xb0
    do_syscall_64+0x3b/0xc0
    entry_SYSCALL_64_after_hwframe+0x44/0xae
    </TASK>

    Fixes: 219b65dcf6c0 ("KVM: SVM: Improve nested interrupt injection")
    Cc: stable@vger.kernel.org
    Co-developed-by: Sean Christopherson <seanjc@google.com>
    Signed-off-by: Sean Christopherson <seanjc@google.com>
    Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
    Message-Id: <35426af6e123cbe91ec7ce5132ce72521f02b1b5.1651440202.git.maciej.szmigiero@oracle.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/x86/kvm/svm/svm.c | 2 --
    1 file changed, 2 deletions(-)

    --- a/arch/x86/kvm/svm/svm.c
    +++ b/arch/x86/kvm/svm/svm.c
    @@ -3417,8 +3417,6 @@ static void svm_set_irq(struct kvm_vcpu
    {
    struct vcpu_svm *svm = to_svm(vcpu);

    - BUG_ON(!(gif_set(svm)));
    -
    trace_kvm_inj_virq(vcpu->arch.interrupt.nr);
    ++vcpu->stat.irq_injections;


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