parisc: speed up flush_tlb_all_local with qemu

PATCH New Helge Deller 1 participant 1 message Aug 12, 2019 PA-RISC architecture

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Helge Deller

author maintainer

2019-08-12 17:13 UTC #0 lore raw

PATCH 1/1 parisc: speed up flush_tlb_all_local with qemu

When started in qemu, we know that qemu will drop all local TLB entries on any pxtlbe instruction. So, if we detect qemu, replace the whole flush_tlb_all_local function by one pdtlbe instruction.

Signed-off-by Helge Deller <[email protected]>

arch/parisc/kernel/pacache.S +9 -0

index df46b0e5a915..fa092ed1e837 100644
@@ -174,6 +174,15 @@ fdtdone:
 
 2:      bv		%r0(%r2)
 	nop
+
+	/*
+	 * When running in qemu, drop whole flush_tlb_all_local function and
+	 * replace by one pdtlbe instruction, for which QEMU will drop all
+	 * local TLB entries.
+	 */
+3:	pdtlbe		%r0(%sr1,%r0)
+	bv,n		%r0(%r2)
+	ALTERNATIVE_CODE(flush_tlb_all_local, 2, ALT_COND_RUN_ON_QEMU, 3b)
 ENDPROC_CFI(flush_tlb_all_local)
 
 	.import cache_info,data