[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v3 1/2] x86/vpmu: Add get/put_vpmu() and VPMU_AVAILABLE
>>> On 22.02.17 at 19:24, <boris.ostrovsky@xxxxxxxxxx> wrote: > vpmu_enabled() (used by hvm/pv_cpuid() to properly report 0xa leaf > for Intel processors) is based on the value of VPMU_CONTEXT_ALLOCATED > bit. This is problematic: > * For HVM guests VPMU context is allocated lazily, during the first > access to VPMU MSRs. Since the leaf is typically queried before guest > attempts to read or write the MSRs it is likely that CPUID will report > no PMU support > * For PV guests the context is allocated eagerly but only in responce to > guest's XENPMU_init hypercall. There is a chance that the guest will > try to read CPUID before making this hypercall. > > This patch introduces VPMU_AVAILABLE flag which is set (subject to vpmu_mode > constraints) during VCPU initialization for both PV and HVM guests. Since > this flag is expected to be managed together with vpmu_count, get/put_vpmu() > are added to simplify code. > > vpmu_enabled() (renamed to vpmu_available()) can now use this new flag. > > (As a side affect this patch also fixes a race in pvpmu_init() where we > increment vcpu_count in vpmu_initialise() after checking vpmu_mode) > > Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> I would have wanted to apply this, but it looks to need re-basing. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |