haraldwolff/qemu-patch-raspberry4
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target-mips: don't flush extra TLB on permissions upgrade

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If the guest uses a TLBWI instruction for upgrading permissions, we
don't need to flush the extra TLBs. This improve boot time performance
by about 10%.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This commit is contained in:
Aurelien Jarno 2012-10-09 21:53:21 +02:00
parent bc3e45e13a
commit 286d52ebfc
1 changed files with 22 additions and 4 deletions
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26
target-mips/op_helper.c
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@ -1819,14 +1819,32 @@ static void r4k_fill_tlb(CPUMIPSState *env, int idx)
void r4k_helper_tlbwi(CPUMIPSState *env)
{
r4k_tlb_t *tlb;
int idx;
target_ulong VPN;
uint8_t ASID;
bool G, V0, D0, V1, D1;
idx = (env->CP0_Index & ~0x80000000) % env->tlb->nb_tlb;
tlb = &env->tlb->mmu.r4k.tlb[idx];
VPN = env->CP0_EntryHi & (TARGET_PAGE_MASK << 1);
#if defined(TARGET_MIPS64)
VPN &= env->SEGMask;
#endif
ASID = env->CP0_EntryHi & 0xff;
G = env->CP0_EntryLo0 & env->CP0_EntryLo1 & 1;
V0 = (env->CP0_EntryLo0 & 2) != 0;
D0 = (env->CP0_EntryLo0 & 4) != 0;
V1 = (env->CP0_EntryLo1 & 2) != 0;
D1 = (env->CP0_EntryLo1 & 4) != 0;
/* Discard cached TLB entries. We could avoid doing this if the
tlbwi is just upgrading access permissions on the current entry;
that might be a further win. */
r4k_mips_tlb_flush_extra (env, env->tlb->nb_tlb);
/* Discard cached TLB entries, unless tlbwi is just upgrading access
permissions on the current entry. */
if (tlb->VPN != VPN || tlb->ASID != ASID || tlb->G != G ||
(tlb->V0 && !V0) || (tlb->D0 && !D0) ||
(tlb->V1 && !V1) || (tlb->D1 && !D1)) {
r4k_mips_tlb_flush_extra(env, env->tlb->nb_tlb);
}
r4k_invalidate_tlb(env, idx, 0);
r4k_fill_tlb(env, idx);