qemu-kvm/kvm-target-i386-kvm-Fix-disabling-MPX-on-cpu-host-with-M.patch
Jon Maloy 5b9676b8f4 * Wed Aug 09 2023 Jon Maloy <jmaloy@redhat.com> - 6.2.0-38
- kvm-qapi-i386-sev-Change-the-reduced-phys-bits-value-fro.patch [bz#2214840]
- kvm-qemu-options.hx-Update-the-reduced-phys-bits-documen.patch [bz#2214840]
- kvm-i386-sev-Update-checks-and-information-related-to-re.patch [bz#2214840]
- kvm-i386-cpu-Update-how-the-EBX-register-of-CPUID-0x8000.patch [bz#2214840]
- kvm-target-i386-kvm-Fix-disabling-MPX-on-cpu-host-with-M.patch [bz#2223947]
- Resolves: bz#2214840
  ([AMDSERVER 8.9 Bug] Qemu SEV reduced-phys-bits fixes)
- Resolves: bz#2223947
  ([RHEL8.9] qemu core dump with '-cpu host,mpx=off' on Cascadelake host)
2023-08-09 23:22:59 +00:00

58 lines
2.4 KiB
Diff

From 522ce31b4998b714b03e781f49403b71531ebe5a Mon Sep 17 00:00:00 2001
From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
Date: Mon, 23 May 2022 18:26:58 +0200
Subject: [PATCH 5/5] target/i386/kvm: Fix disabling MPX on "-cpu host" with
MPX-capable host
RH-Author: Ani Sinha <None>
RH-MergeRequest: 297: target/i386/kvm: Fix disabling MPX on "-cpu host" with MPX-capable host
RH-Bugzilla: 2223947
RH-Acked-by: Vitaly Kuznetsov <vkuznets@redhat.com>
RH-Acked-by: Jon Maloy <jmaloy@redhat.com>
RH-Commit: [1/1] 90098294a873a53b366389606fd0402efcbd70ad
Since KVM commit 5f76f6f5ff96 ("KVM: nVMX: Do not expose MPX VMX controls when guest MPX disabled")
it is not possible to disable MPX on a "-cpu host" just by adding "-mpx"
there if the host CPU does indeed support MPX.
QEMU will fail to set MSR_IA32_VMX_TRUE_{EXIT,ENTRY}_CTLS MSRs in this case
and so trigger an assertion failure.
Instead, besides "-mpx" one has to explicitly add also
"-vmx-exit-clear-bndcfgs" and "-vmx-entry-load-bndcfgs" to QEMU command
line to make it work, which is a bit convoluted.
Make the MPX-related bits in FEAT_VMX_{EXIT,ENTRY}_CTLS dependent on MPX
being actually enabled so such workarounds are no longer necessary.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <51aa2125c76363204cc23c27165e778097c33f0b.1653323077.git.maciej.szmigiero@oracle.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 267b5e7e378afd260004cb37a66a6fcd641e3b53)
---
target/i386/cpu.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 265f0aadfc..726814ee2e 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -1326,6 +1326,14 @@ static FeatureDep feature_dependencies[] = {
.from = { FEAT_7_0_EBX, CPUID_7_0_EBX_INVPCID },
.to = { FEAT_VMX_SECONDARY_CTLS, VMX_SECONDARY_EXEC_ENABLE_INVPCID },
},
+ {
+ .from = { FEAT_7_0_EBX, CPUID_7_0_EBX_MPX },
+ .to = { FEAT_VMX_EXIT_CTLS, VMX_VM_EXIT_CLEAR_BNDCFGS },
+ },
+ {
+ .from = { FEAT_7_0_EBX, CPUID_7_0_EBX_MPX },
+ .to = { FEAT_VMX_ENTRY_CTLS, VMX_VM_ENTRY_LOAD_BNDCFGS },
+ },
{
.from = { FEAT_7_0_EBX, CPUID_7_0_EBX_RDSEED },
.to = { FEAT_VMX_SECONDARY_CTLS, VMX_SECONDARY_EXEC_RDSEED_EXITING },
--
2.37.3