Re: [Xen-devel] [PATCH] x86/HVM: extend LAPIC shortcuts around P2M lookups

[Tim Deegan <tim@xxxxxxx>]

At 14:43 +0100 on 01 Aug (1406900582), Jan Beulich wrote:
> ... to all internally handled MMIO regions. It is in particular the
> HPET page that, e.g. on Windows Server 2012 R2, can get heavily
> accessed, and hence avoiding the unnecessary lookups is rather
> beneficial (in the reported case a 40+-vCPU guest would previously not
> have booted at all while with hvm_hap_nested_page_fault() shortcut
> alone it was able to boot up in 18 minutes [i.e. still room for
> improvement]).
> 
> Note the apparently unrelated addition of a is_hvm_vcpu() check to the
> __hvm_copy() code: Afaict for PVH this shortcut should never have taken
> effect (since there's no LAPIC in that case).
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Reviewed-by: Tim Deegan <tim@xxxxxxx>


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