iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

KVM: MIPS: Drop dubious EntryHi optimisation

Browse Source 
There exists a slightly dubious optimisation in the implementation of
the MIPS KVM EntryHi emulation which skips TLB invalidation if the
EntryHi points to an address in the guest KSeg0 region, intended to
catch guest TLB invalidations where the ASID is almost immediately
restored to the previous value.

Now that we perform lazy host ASID regeneration for guest user mode when
the guest ASID changes we should be able to drop the optimisation
without a significant impact (only the extra TLB refills for the small
amount of code while the TLB is being invalidated).

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
This commit is contained in:
James Hogan 2016-09-16 13:14:09 +01:00
parent 25b08c7fb0
commit bf18db4e7b
1 changed files with 1 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/mips/kvm/emulate.c
View File

@ -1162,8 +1162,7 @@ enum emulation_result kvm_mips_emulate_CP0(union mips_instruction inst,
} else if (rd == MIPS_CP0_TLB_HI && sel == 0) {
u32 nasid =
vcpu->arch.gprs[rt] & KVM_ENTRYHI_ASID;
if ((KSEGX(vcpu->arch.gprs[rt]) != CKSEG0) &&
((kvm_read_c0_guest_entryhi(cop0) &
if (((kvm_read_c0_guest_entryhi(cop0) &
KVM_ENTRYHI_ASID) != nasid)) {
trace_kvm_asid_change(vcpu,
kvm_read_c0_guest_entryhi(cop0)