[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 0/2] xen/pci: Use APIC for MSIs when APIC virtualization is supported
On Tue, Dec 02, 2014 at 03:19:11PM -0500, Boris Ostrovsky wrote: > Changes in v4: > * Added comment describing what we check for in pci_xen_init() > Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> > Changes in v3: > * Explicitly include asm/apic.h in arch/x86/pci/xen.c for !CONFIG_SMP. > > 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 > > arch/x86/include/asm/xen/cpuid.h | 91 > ++++++++++++++++++++++++++++++++++++++++ > arch/x86/pci/xen.c | 31 +++++++++++++- > 2 files changed, 120 insertions(+), 2 deletions(-) > create mode 100644 arch/x86/include/asm/xen/cpuid.h > > -- > 1.8.1.4 > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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