From 522ce31b4998b714b03e781f49403b71531ebe5a Mon Sep 17 00:00:00 2001 From: "Maciej S. Szmigiero" 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 RH-MergeRequest: 297: target/i386/kvm: Fix disabling MPX on "-cpu host" with MPX-capable host RH-Bugzilla: 2223947 RH-Acked-by: Vitaly Kuznetsov RH-Acked-by: Jon Maloy 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 Message-Id: <51aa2125c76363204cc23c27165e778097c33f0b.1653323077.git.maciej.szmigiero@oracle.com> Cc: qemu-stable@nongnu.org Signed-off-by: Paolo Bonzini (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