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linux/arch/x86/kvm/mmu
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Maciej S. Szmigiero 8f5c44f953 KVM: x86/mmu: Make HVA handler retpoline-friendly 
When retpolines are enabled they have high overhead in the inner loop
inside kvm_handle_hva_range() that iterates over the provided memory area.

Let's mark this function and its TDP MMU equivalent __always_inline so
compiler will be able to change the call to the actual handler function
inside each of them into a direct one.

This significantly improves performance on the unmap test on the existing
kernel memslot code (tested on a Xeon 8167M machine):
30 slots in use:
Test       Before   After     Improvement
Unmap      0.0353s  0.0334s   5%
Unmap 2M   0.00104s 0.000407s 61%

509 slots in use:
Test       Before   After     Improvement
Unmap      0.0742s  0.0740s   None
Unmap 2M   0.00221s 0.00159s  28%

Looks like having an indirect call in these functions (and, so, a
retpoline) might have interfered with unrolling of the whole loop in the
CPU.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <732d3fe9eb68aa08402a638ab0309199fa89ae56.1612810129.git.maciej.szmigiero@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-02-09 08:42:09 -05:00
..
mmu_audit.c KVM: Stop using deprecated jump label APIs 2021-02-04 05:27:29 -05:00
mmu_internal.h KVM: x86: compile out TDP MMU on 32-bit systems 2021-02-08 14:49:01 -05:00
mmu.c KVM: x86/mmu: Make HVA handler retpoline-friendly 2021-02-09 08:42:09 -05:00
mmutrace.h kvm: x86/mmu: Add TDP MMU SPTE changed trace point 2020-11-19 10:57:16 -05:00
page_track.c KVM: x86/mmu: Use an rwlock for the x86 MMU 2021-02-04 05:27:43 -05:00
paging_tmpl.h KVM: x86/mmu: Use an rwlock for the x86 MMU 2021-02-04 05:27:43 -05:00
spte.c KVM: x86: use static calls to reduce kvm_x86_ops overhead 2021-02-04 05:27:30 -05:00
spte.h KVM: x86/mmu: Flush TLBs after zap in TDP MMU PF handler 2021-02-04 05:27:44 -05:00
tdp_iter.c KVM: x86/mmu: Protect TDP MMU page table memory with RCU 2021-02-04 05:27:42 -05:00
tdp_iter.h KVM: x86/mmu: Protect TDP MMU page table memory with RCU 2021-02-04 05:27:42 -05:00
tdp_mmu.c KVM: x86/mmu: Make HVA handler retpoline-friendly 2021-02-09 08:42:09 -05:00
tdp_mmu.h KVM: x86: compile out TDP MMU on 32-bit systems 2021-02-08 14:49:01 -05:00