> Author: cem
> Date: Fri Jan 18 23:54:51 2019
> New Revision: 343166
> URL: https://svnweb.freebsd.org/changeset/base/343166
>
> Log:
> vmm(4): Mask Spectre feature bits on AMD hosts
>
> For parity with Intel hosts, which already mask out the CPUID feature
> bits that indicate the presence of the SPEC_CTRL MSR, do the same on
> AMD.
>
> Eventually we may want to have a better support story for guests, but
> for now, limit the damage of incorrectly indicating an MSR we do not yet
> support.
>
> Eventually, we may want a generic CPUID override system for
> administrators, or for minimum supported feature set in heterogenous
> environments with failover. That is a much larger scope effort than
> this bug fix.
This area has a MAINTAINERS line, could you please respect it.
> PR: 235010
> Reported by: Rys Sommefeldt <rys AT sommefeldt.com>
> Sponsored by: Dell EMC Isilon
>
> Modified:
> head/sys/amd64/vmm/x86.c
>
> Modified: head/sys/amd64/vmm/x86.c
> ==============================================================================
> --- head/sys/amd64/vmm/x86.c Fri Jan 18 23:26:31 2019 (r343165)
> +++ head/sys/amd64/vmm/x86.c Fri Jan 18 23:54:51 2019 (r343166)
> @@ -136,6 +136,14 @@ x86_emulate_cpuid(struct vm *vm, int vcpu_id,
> case CPUID_8000_0008:
> cpuid_count(*eax, *ecx, regs);
> if (vmm_is_amd()) {
> + /*
> + * As on Intel (0000_0007:0, EDX), mask out
> + * unsupported or unsafe AMD extended features
> + * (8000_0008 EBX).
> + */
> + regs[1] &= (AMDFEID_CLZERO | AMDFEID_IRPERF |
> + AMDFEID_XSAVEERPTR);
> +
> vm_get_topology(vm, &sockets, &cores, &threads,
> &maxcpus);
> /*
>
>
--
Rod Grimes rgri...@freebsd.org
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