>>> On 08.07.16 at 14:29, <david.vra...@citrix.com> wrote: > On 08/07/16 13:15, Jan Beulich wrote: >> As of Xen 4.7 PV CPUID doesn't expose either of CPUID[1].ECX[7] and >> CPUID[0x80000007].EDX[7] anymore, causing the driver to fail to load on >> both Intel and AMD systems. Doing any kind of hardware capability >> checks in the driver as a prerequisite was wrong anyway: With the >> hypervisor being in charge, all such checking should be done by it. If >> ACPI data gets uploaded despite some missing capability, the hypervisor >> is free to ignore part or all of that data. >> >> Ditch the entire check_prereq() function, and do the only valid check >> (xen_initial_domain()) in the caller in its place. > > Thanks, but I'm not sure this is sufficient. I think the generic ACPI > code needs to know the full capabilities in order to generate the > correct tables, or you won't get (for example) turbo mode working. > > We had to fake the EST feature back in. > > --- a/arch/x86/xen/enlighten.c > +++ b/arch/x86/xen/enlighten.c > @@ -448,7 +448,8 @@ static void __init xen_init_cpuid_mask(void) > if ((cx & xsave_mask) != xsave_mask) > cpuid_leaf1_ecx_mask &= ~xsave_mask; /* disable XSAVE & OSXSAVE > */ > if (xen_check_mwait()) > - cpuid_leaf1_ecx_set_mask = (1 << (X86_FEATURE_MWAIT % 32)); > + cpuid_leaf1_ecx_set_mask = (1 << (X86_FEATURE_MWAIT % 32) > + | 1 << (X86_FEATURE_EST % 32)); > } > > static void xen_set_debugreg(int reg, unsigned long val)
Hmm, interesting. I admit I only tested on an AMD system, so I can't exclude the above is necessary. Otoh going over generic ACPI code the only use of X86_FEATURE_EST controls the logging of a message. Plus there's a use in arch_acpi_set_pdc_bits() - perhaps that's the one you mean? There's certainly no use of X86_FEATURE_HW_PSTATE anywhere in relevant code, so the AMD side would appear to be fine (which matches my testing). So I think the patch is fine as is (also avoiding cross component adjustments), and the part you suggest may then better be a separate patch? Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel