From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A262E1B21B7 for ; Tue, 18 Feb 2025 11:27:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739878022; cv=none; b=O8hgCUsawX3ykdDxvNcVAJVPy9sbaL4ydR12G0Zub4Hfa6pdIbRCJJso+rHMT25p+MXYVPHyWmyDdKKNIB2m8hs9JJBacGZf/WgjLZ+WM8ADVe3HB28vKiR4X+5pxHLDdi5T9hm0Cy9AW/JosMNB7KXiids80y7960wUMmrmPwM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739878022; c=relaxed/simple; bh=Eo+bBBYOzwYpn4IOHmgnpRRldKcT9AoNiBqDH0jwcjY=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=U8sCLQafSN8SmekT2YO/GL7iUguP/XUpJm5y3gBYIuaCJxXIqZrQ5AgOCyhKhwkIesDYGonPDfhu1gd5BYPFQeqNfN7eLm9qzU09Naacby2U1VMnCbOqGKHyWNsjt6SHFpNtL9tZFmeUY7KIqwPXQSz35Fz9PYSFu6dq5wt4YZg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ejVeuVgL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ejVeuVgL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 05B55C4CEE6; Tue, 18 Feb 2025 11:27:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1739878022; bh=Eo+bBBYOzwYpn4IOHmgnpRRldKcT9AoNiBqDH0jwcjY=; h=Subject:To:Cc:From:Date:From; b=ejVeuVgLvtGjv8pGj6zapuGvkFUkykMkQT4z7X5ttExBx9PddOnCKn1/EldVz2pw9 jmlprQGQH4BmFqEfcdtRN+PzH3w0RFbg46dgaaX7Pd3CtLNLw2QpX9+SaH5LRRAGYv qiT7+hIzkpT5N8rdL4MESN6XfyFpwYMuEl1r1dOw= Subject: FAILED: patch "[PATCH] KVM: x86: Reject Hyper-V's SEND_IPI hypercalls if local APIC" failed to apply to 5.4-stable tree To: seanjc@google.com,vkuznets@redhat.com,zoudongjie@huawei.com Cc: From: Date: Tue, 18 Feb 2025 12:26:51 +0100 Message-ID: <2025021851-nautical-buffoon-d8b1@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.4-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 . 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-5.4.y git checkout FETCH_HEAD git cherry-pick -x a8de7f100bb5989d9c3627d3a223ee1c863f3b69 # git commit -s git send-email --to '' --in-reply-to '2025021851-nautical-buffoon-d8b1@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From a8de7f100bb5989d9c3627d3a223ee1c863f3b69 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 17 Jan 2025 16:34:51 -0800 Subject: [PATCH] KVM: x86: Reject Hyper-V's SEND_IPI hypercalls if local APIC isn't in-kernel 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 on userspace to opt-in to KVM_CAP_HYPERV_ENFORCE_CPUID. Rejecting SEND_IPI and SEND_IPI_EX fixes a NULL-pointer dereference if Hyper-V enlightenments are exposed to the guest without an in-kernel local APIC: dump_stack+0xbe/0xfd __kasan_report.cold+0x34/0x84 kasan_report+0x3a/0x50 __apic_accept_irq+0x3a/0x5c0 kvm_hv_send_ipi.isra.0+0x34e/0x820 kvm_hv_hypercall+0x8d9/0x9d0 kvm_emulate_hypercall+0x506/0x7e0 __vmx_handle_exit+0x283/0xb60 vmx_handle_exit+0x1d/0xd0 vcpu_enter_guest+0x16b0/0x24c0 vcpu_run+0xc0/0x550 kvm_arch_vcpu_ioctl_run+0x170/0x6d0 kvm_vcpu_ioctl+0x413/0xb20 __se_sys_ioctl+0x111/0x160 do_syscal1_64+0x30/0x40 entry_SYSCALL_64_after_hwframe+0x67/0xd1 Note, checking the sending vCPU is sufficient, as the per-VM irqchip_mode can't be modified after vCPUs are created, i.e. if one vCPU has an in-kernel local APIC, then all vCPUs have an in-kernel local APIC. Reported-by: Dongjie Zou Fixes: 214ff83d4473 ("KVM: x86: hyperv: implement PV IPI send hypercalls") Fixes: 2bc39970e932 ("x86/kvm/hyper-v: Introduce KVM_GET_SUPPORTED_HV_CPUID") Cc: stable@vger.kernel.org Reviewed-by: Vitaly Kuznetsov Link: https://lore.kernel.org/r/20250118003454.2619573-2-seanjc@google.com Signed-off-by: Sean Christopherson diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 6a6dd5a84f22..6ebeb6cea6c0 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -2226,6 +2226,9 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) u32 vector; bool all_cpus; + if (!lapic_in_kernel(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, @@ -2852,7 +2855,8 @@ int kvm_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; - ent->eax |= HV_X64_CLUSTER_IPI_RECOMMENDED; + if (!vcpu || lapic_in_kernel(vcpu)) + ent->eax |= HV_X64_CLUSTER_IPI_RECOMMENDED; ent->eax |= HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED; if (evmcs_ver) ent->eax |= HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;