KVM: TDX: Enable guest access to LMCE related MSRs

Browse source

Allow TDX guest to configure LMCE (Local Machine Check Event) by handling
MSR IA32_FEAT_CTL and IA32_MCG_EXT_CTL.

MCE and MCA are advertised via cpuid based on the TDX module spec.  Guest
kernel can access IA32_FEAT_CTL to check whether LMCE is opted-in by the
platform or not.  If LMCE is opted-in by the platform, guest kernel can
access IA32_MCG_EXT_CTL to enable/disable LMCE.

Handle MSR IA32_FEAT_CTL and IA32_MCG_EXT_CTL for TDX guests to avoid
failure when a guest accesses them with TDG.VP.VMCALL<MSR> on #VE.  E.g.,
Linux guest will treat the failure as a #GP(0).

Userspace VMM may not opt-in LMCE by default, e.g., QEMU disables it by
default, "-cpu lmce=on" is needed in QEMU command line to opt-in it.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
[binbin: rework changelog]
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Message-ID: <20250227012021.1778144-11-binbin.wu@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

...

This commit is contained in:

Isaku Yamahata 2025-02-27 09:20:11 +08:00 • committed by Paolo Bonzini

parent 081385dbc6

commit 9fc3402a20

1 changed files with 37 additions and 9 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

46

arch/x86/kvm/vmx/tdx.c

View file