KVM: ppc: Write only modified shadow entries into the TLB on exit
Track which TLB entries need to be written, instead of overwriting everything
below the high water mark. Typically only a single guest TLB entry will be
modified in a single exit.
Guest boot time performance improvement: about 15%.
Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/arch/powerpc/kvm/booke_interrupts.S b/arch/powerpc/kvm/booke_interrupts.S
index 3e88dfa..564ea32 100644
--- a/arch/powerpc/kvm/booke_interrupts.S
+++ b/arch/powerpc/kvm/booke_interrupts.S
@@ -335,7 +335,7 @@
lwz r3, VCPU_PID(r4)
mtspr SPRN_PID, r3
- /* Prevent all TLB updates. */
+ /* Prevent all asynchronous TLB updates. */
mfmsr r5
lis r6, (MSR_EE|MSR_CE|MSR_ME|MSR_DE)@h
ori r6, r6, (MSR_EE|MSR_CE|MSR_ME|MSR_DE)@l
@@ -344,27 +344,44 @@
/* Load the guest mappings, leaving the host's "pinned" kernel mappings
* in place. */
- /* XXX optimization: load only modified guest entries. */
mfspr r10, SPRN_MMUCR /* Save host MMUCR. */
- lis r8, tlb_44x_hwater@ha
- lwz r8, tlb_44x_hwater@l(r8)
- addi r9, r4, VCPU_SHADOW_TLB - 4
+ li r5, PPC44x_TLB_SIZE
+ lis r5, tlb_44x_hwater@ha
+ lwz r5, tlb_44x_hwater@l(r5)
+ mtctr r5
+ addi r9, r4, VCPU_SHADOW_TLB
+ addi r5, r4, VCPU_SHADOW_MOD
+ li r3, 0
+1:
+ lbzx r7, r3, r5
+ cmpwi r7, 0
+ beq 3f
+
+ /* Load guest entry. */
+ mulli r11, r3, TLBE_BYTES
+ add r11, r11, r9
+ lwz r7, 0(r11)
+ mtspr SPRN_MMUCR, r7
+ lwz r7, 4(r11)
+ tlbwe r7, r3, PPC44x_TLB_PAGEID
+ lwz r7, 8(r11)
+ tlbwe r7, r3, PPC44x_TLB_XLAT
+ lwz r7, 12(r11)
+ tlbwe r7, r3, PPC44x_TLB_ATTRIB
+3:
+ addi r3, r3, 1 /* Increment index. */
+ bdnz 1b
+
+ mtspr SPRN_MMUCR, r10 /* Restore host MMUCR. */
+
+ /* Clear bitmap of modified TLB entries */
+ li r5, PPC44x_TLB_SIZE>>2
+ mtctr r5
+ addi r5, r4, VCPU_SHADOW_MOD - 4
li r6, 0
1:
- /* Load guest entry. */
- lwzu r7, 4(r9)
- mtspr SPRN_MMUCR, r7
- lwzu r7, 4(r9)
- tlbwe r7, r6, PPC44x_TLB_PAGEID
- lwzu r7, 4(r9)
- tlbwe r7, r6, PPC44x_TLB_XLAT
- lwzu r7, 4(r9)
- tlbwe r7, r6, PPC44x_TLB_ATTRIB
- /* Increment index. */
- addi r6, r6, 1
- cmpw r6, r8
- blt 1b
- mtspr SPRN_MMUCR, r10 /* Restore host MMUCR. */
+ stwu r6, 4(r5)
+ bdnz 1b
iccci 0, 0 /* XXX hack */