[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 02/12/2014 20:48, Konrad Rzeszutek Wilk wrote: > 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> Reviewed-by: Andrew Cooper <andrew.cooper3@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 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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