Re: [PATCH v4 5/7] KVM: x86: Virtualize LASS and advertise support to userspace
Binbin Wu <[email protected]>
| Newsgroups | org.kernel.vger.kvm,org.kernel.vger.linux-kernel,org.kernel.vger.linux-kselftest |
|---|---|
| Message-ID | <[email protected]> |
On 8/6/2026 9:15 AM, Sohil Mehta wrote: > From: Zeng Guang <[email protected]> > > Virtualize Linear Address Space Separation (LASS) by letting the guest > enable CR4.LASS[bit 27]. Allow the guest to set CR4.LASS only if LASS is > enumerated in the guest's CPUID. Set CR4.LASS in the emulated > IA32_VMX_CR4_FIXED1 MSR so that LASS can be enabled in nested VMX > operation as well. > > Keep CR4.LASS KVM-owned instead of making it guest-owned. LASS is > expected to be enabled once per vCPU at boot and rarely toggled at > runtime. > > LASS is enumerated by CPUID.(EAX=07H,ECX=1):EAX.LASS[bit 6] and only > works in IA-32e mode. Advertise LASS to userspace on 64-bit kernels and > only when it is supported by the host. Notably, it will not be exposed > to userspace if the deprecated vsyscall=emulate mode is set on the ^ Nit: mode could be dropped. > kernel command line. > > Signed-off-by: Zeng Guang <[email protected]> > Signed-off-by: Binbin Wu <[email protected]> > Signed-off-by: Sohil Mehta <[email protected]> Reviewed-by: Binbin Wu <[email protected]>