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 F1C76257435; Mon, 23 Mar 2026 15:24:32 +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=1774279473; cv=none; b=JGq++pn5kbahmh19c1KcwZl8SVOyyDwwBoBUZf6AOd3zLYQONMLnHLYDMIEAsolGE82Js4j21T1A/RFATLz1A0Jq7QZ03GEMpzGjDIMEMFDlDdPavHWjObjqp42pamLJTc5oDVaTQIzcFdjiaefl27mtQIquXnitWtqlb1mPOlU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774279473; c=relaxed/simple; bh=bHeR0kePWbCvxVPy9QmWgfI0YmBd4DnRUx0zcPq5Fu4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rvV90J3KKSkBLnHirV2mw/7Y0Jp9Py5B5j6NgGHeIesNwDAQJ2+0o67w7GnSQP/rj0tKGeM9K7tO5FVCeejmoC+pr2xNdITTj2n0+SpGNK9e1etoo3T0nsiymxMAOk/5Is2MCixrzKZadYkJpt2HVTe8NKe32ojRWEnvamP8JOU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FOQroLMn; 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="FOQroLMn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3ADB1C4CEF7; Mon, 23 Mar 2026 15:24:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774279472; bh=bHeR0kePWbCvxVPy9QmWgfI0YmBd4DnRUx0zcPq5Fu4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FOQroLMnBR/yiXrmfCxSYhYcrzsK0A4naZdroV6lNC2r+1698BNAG0dAdE9U2GaQg V03sF9OdE7YCE42akHCeVSf7Fg4zQSc8sUxHt/j2jxNX2qsv01eo0zKbFkd0uWQFUt BQd9zOh2a3wJ8P0Xvxk8s4gzt8i4k+vG9la8h1eA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jim Mattson , Sean Christopherson , Sasha Levin Subject: [PATCH 6.1 029/481] KVM: x86: Return "unsupported" instead of "invalid" on access to unsupported PV MSR Date: Mon, 23 Mar 2026 14:40:11 +0100 Message-ID: <20260323134525.951431151@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260323134525.256603107@linuxfoundation.org> References: <20260323134525.256603107@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sean Christopherson [ Upstream commit 5bb9ac1865123356337a389af935d3913ee917ed ] Return KVM_MSR_RET_UNSUPPORTED instead of '1' (which for all intents and purposes means "invalid") when rejecting accesses to KVM PV MSRs to adhere to KVM's ABI of allowing host reads and writes of '0' to MSRs that are advertised to userspace via KVM_GET_MSR_INDEX_LIST, even if the vCPU model doesn't support the MSR. E.g. running a QEMU VM with -cpu host,-kvmclock,kvm-pv-enforce-cpuid yields: qemu: error: failed to set MSR 0x12 to 0x0 qemu: target/i386/kvm/kvm.c:3301: kvm_buf_set_msrs: Assertion `ret == cpu->kvm_msr_buf->nmsrs' failed. Fixes: 66570e966dd9 ("kvm: x86: only provide PV features if enabled in guest's CPUID") Cc: stable@vger.kernel.org Reviewed-by: Jim Mattson Link: https://patch.msgid.link/20251230205948.4094097-1-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Sasha Levin --- arch/x86/kvm/x86.c | 40 ++++++++++++++++++++-------------------- 1 file changed, 20 insertions(+), 20 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 84e54547ec7d0..b6fdf084fc92a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3731,47 +3731,47 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) break; case MSR_KVM_WALL_CLOCK_NEW: if (!guest_pv_has(vcpu, KVM_FEATURE_CLOCKSOURCE2)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; vcpu->kvm->arch.wall_clock = data; kvm_write_wall_clock(vcpu->kvm, data, 0); break; case MSR_KVM_WALL_CLOCK: if (!guest_pv_has(vcpu, KVM_FEATURE_CLOCKSOURCE)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; vcpu->kvm->arch.wall_clock = data; kvm_write_wall_clock(vcpu->kvm, data, 0); break; case MSR_KVM_SYSTEM_TIME_NEW: if (!guest_pv_has(vcpu, KVM_FEATURE_CLOCKSOURCE2)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; kvm_write_system_time(vcpu, data, false, msr_info->host_initiated); break; case MSR_KVM_SYSTEM_TIME: if (!guest_pv_has(vcpu, KVM_FEATURE_CLOCKSOURCE)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; kvm_write_system_time(vcpu, data, true, msr_info->host_initiated); break; case MSR_KVM_ASYNC_PF_EN: if (!guest_pv_has(vcpu, KVM_FEATURE_ASYNC_PF)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; if (kvm_pv_enable_async_pf(vcpu, data)) return 1; break; case MSR_KVM_ASYNC_PF_INT: if (!guest_pv_has(vcpu, KVM_FEATURE_ASYNC_PF_INT)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; if (kvm_pv_enable_async_pf_int(vcpu, data)) return 1; break; case MSR_KVM_ASYNC_PF_ACK: if (!guest_pv_has(vcpu, KVM_FEATURE_ASYNC_PF_INT)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; if (data & 0x1) { vcpu->arch.apf.pageready_pending = false; kvm_check_async_pf_completion(vcpu); @@ -3779,7 +3779,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) break; case MSR_KVM_STEAL_TIME: if (!guest_pv_has(vcpu, KVM_FEATURE_STEAL_TIME)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; if (unlikely(!sched_info_on())) return 1; @@ -3797,7 +3797,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) break; case MSR_KVM_PV_EOI_EN: if (!guest_pv_has(vcpu, KVM_FEATURE_PV_EOI)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; if (kvm_lapic_set_pv_eoi(vcpu, data, sizeof(u8))) return 1; @@ -3805,7 +3805,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) case MSR_KVM_POLL_CONTROL: if (!guest_pv_has(vcpu, KVM_FEATURE_POLL_CONTROL)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; /* only enable bit supported */ if (data & (-1ULL << 1)) @@ -4108,61 +4108,61 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) break; case MSR_KVM_WALL_CLOCK: if (!guest_pv_has(vcpu, KVM_FEATURE_CLOCKSOURCE)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; msr_info->data = vcpu->kvm->arch.wall_clock; break; case MSR_KVM_WALL_CLOCK_NEW: if (!guest_pv_has(vcpu, KVM_FEATURE_CLOCKSOURCE2)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; msr_info->data = vcpu->kvm->arch.wall_clock; break; case MSR_KVM_SYSTEM_TIME: if (!guest_pv_has(vcpu, KVM_FEATURE_CLOCKSOURCE)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; msr_info->data = vcpu->arch.time; break; case MSR_KVM_SYSTEM_TIME_NEW: if (!guest_pv_has(vcpu, KVM_FEATURE_CLOCKSOURCE2)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; msr_info->data = vcpu->arch.time; break; case MSR_KVM_ASYNC_PF_EN: if (!guest_pv_has(vcpu, KVM_FEATURE_ASYNC_PF)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; msr_info->data = vcpu->arch.apf.msr_en_val; break; case MSR_KVM_ASYNC_PF_INT: if (!guest_pv_has(vcpu, KVM_FEATURE_ASYNC_PF_INT)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; msr_info->data = vcpu->arch.apf.msr_int_val; break; case MSR_KVM_ASYNC_PF_ACK: if (!guest_pv_has(vcpu, KVM_FEATURE_ASYNC_PF_INT)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; msr_info->data = 0; break; case MSR_KVM_STEAL_TIME: if (!guest_pv_has(vcpu, KVM_FEATURE_STEAL_TIME)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; msr_info->data = vcpu->arch.st.msr_val; break; case MSR_KVM_PV_EOI_EN: if (!guest_pv_has(vcpu, KVM_FEATURE_PV_EOI)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; msr_info->data = vcpu->arch.pv_eoi.msr_val; break; case MSR_KVM_POLL_CONTROL: if (!guest_pv_has(vcpu, KVM_FEATURE_POLL_CONTROL)) - return 1; + return KVM_MSR_RET_UNSUPPORTED; msr_info->data = vcpu->arch.msr_kvm_poll_control; break; -- 2.51.0