Messages in this thread | | | Date | Wed, 29 Oct 2014 13:59:42 +0000 | From | David Vrabel <> | Subject | Re: [Xen-devel] [PATCH v2 0/2] xen/pci: Use APIC for MSIs when APIC virtualization is supported |
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On 27/10/14 16:05, Boris Ostrovsky wrote: > Changes in v2: > * New version of cpuid.h file from Xen tree (with a couple of style adjustments) > * Whitespace cleanup > > Currently HVM guests handle MSI interrupts using pirqs/event channels, allowing > us to not issue APIC accesses that result in somewhat expensive VMEXITs. When > hardware supports APIC virtualization we don't need to use pirqs anymore > since now guest's APIC accesses can be handled by the processor itself. > > There are two patches in this series: > > 1. Move setting of x86_msi ops to a later point. The reason for doing so is that > we currently decide whether or not to use pirqs before kernel had a chance to > see whether it should be using x2APIC instead of plain APIC. Since hardware may > virtualize either or both of those two we can only make pirqs vs. APIC selection > after kernel has settled down on which APIC version it will use. (Note that > currently x2APIC is not used by HVM guests so technically this patch is not > necessary. However, it probably makes sense to apply it now to avoid > forgetting to do it when we enable x2APIC). > > 2. Set x86_msi ops to use pirqs only when APIC virtualization is not available. > The commit message describes performance improvements that this change brings. > > Boris Ostrovsky (2): > xen/pci: Defer initialization of MSI ops on HVM guests until after > x2APIC has been set up > xen/pci: Use APIC directly when APIC virtualization is supported by > hardware
Applied to devel/for-linus-3.19.
Thanks.
David
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