From: Maciej S. Szmigiero Date: Mon, 23 May 2022 16:26:58 +0000 (+0200) Subject: target/i386/kvm: Fix disabling MPX on "-cpu host" with MPX-capable host X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=267b5e7e378afd260004cb37a66a6fcd641e3b53;p=qemu.git target/i386/kvm: Fix disabling MPX on "-cpu host" with MPX-capable host 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 --- diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 35c3475e6c..385691458f 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -1355,6 +1355,14 @@ 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 },