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Date: Fri, 17 Feb 2017 09:05:09 -0500 From: Boris Ostrovsky <boris.ostrovsky@...cle.com> To: Juergen Gross <jgross@...e.com>, linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org, x86@...nel.org Cc: hpa@...or.com, tglx@...utronix.de, mingo@...hat.com Subject: Re: [PATCH 2/2] x86/xen: use capabilities instead of fake cpuid values On 02/17/2017 02:36 AM, Juergen Gross wrote: > When running as pv domain xen_cpuid() is being used instead of > native_cpuid(). In xen_cpuid() the aperf/mperf feature is indicated > as not being present by special casing the related cpuid leaf. > > Instead of delivering fake cpuid values clear the cpu capability bit > for aperf/mperf instead. > > Signed-off-by: Juergen Gross <jgross@...e.com> > --- > arch/x86/xen/enlighten.c | 11 +++-------- > 1 file changed, 3 insertions(+), 8 deletions(-) > > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c > index 83399ce..0eebb75 100644 > --- a/arch/x86/xen/enlighten.c > +++ b/arch/x86/xen/enlighten.c > @@ -301,9 +301,6 @@ xen_running_on_version_or_later(unsigned int major, unsigned int minor) > return false; > } > > -#define CPUID_THERM_POWER_LEAF 6 > -#define APERFMPERF_PRESENT 0 > - > static __read_mostly unsigned int cpuid_leaf1_edx_mask = ~0; > static __read_mostly unsigned int cpuid_leaf1_ecx_mask = ~0; > > @@ -337,11 +334,6 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx, > *dx = cpuid_leaf5_edx_val; > return; > > - case CPUID_THERM_POWER_LEAF: > - /* Disabling APERFMPERF for kernel usage */ > - maskecx = ~(1 << APERFMPERF_PRESENT); > - break; > - But now APERF/MPERF will be reported as supported by CPUID, won't it? > case 0xb: > /* Suppress extended topology stuff */ > maskebx = 0; > @@ -462,6 +454,9 @@ static void __init xen_init_cpuid_mask(void) > if (xen_check_mwait()) > cpuid_leaf1_ecx_set_mask = (1 << (X86_FEATURE_MWAIT % 32)); > > + /* Disable APERFMPERF feature. */ > + setup_clear_cpu_cap(X86_FEATURE_APERFMPERF); > + > /* Disable DCA feature. */ > setup_clear_cpu_cap(X86_FEATURE_DCA); I think both of those can go to xen_set_cpu_features(). -boris
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