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util/cacheflush: Optimize flushing when ppc host has coherent icache

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On linux, the AT_HWCAP bit PPC_FEATURE_ICACHE_SNOOP indicates
that we can use a simplified 3 instruction flush sequence.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Message-Id: <20220519141131.29839-1-npiggin@gmail.com>
[rth: update after merging cacheflush.c and cacheinfo.c]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20220621014837.189139-4-richard.henderson@linaro.org>
This commit is contained in:
Nicholas Piggin 2022-06-20 18:48:37 -07:00 committed by Richard Henderson
parent bdd50dc7d0
commit c79a8e840c
1 changed files with 23 additions and 2 deletions
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25
util/cacheflush.c
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@ -117,6 +117,10 @@ static void sys_cache_info(int *isize, int *dsize)
* Architecture (+ OS) specific cache detection mechanisms.
*/
#if defined(__powerpc__)
static bool have_coherent_icache;
#endif
#if defined(__aarch64__) && !defined(CONFIG_DARWIN)
/* Apple does not expose CTR_EL0, so we must use system interfaces. */
static uint64_t save_ctr_el0;
@ -156,6 +160,7 @@ static void arch_cache_info(int *isize, int *dsize)
if (*dsize == 0) {
*dsize = qemu_getauxval(AT_DCACHEBSIZE);
}
have_coherent_icache = qemu_getauxval(AT_HWCAP) & PPC_FEATURE_ICACHE_SNOOP;
}
#else
@ -298,8 +303,24 @@ void flush_idcache_range(uintptr_t rx, uintptr_t rw, size_t len)
void flush_idcache_range(uintptr_t rx, uintptr_t rw, size_t len)
{
uintptr_t p, b, e;
size_t dsize = qemu_dcache_linesize;
size_t isize = qemu_icache_linesize;
size_t dsize, isize;
/*
* Some processors have coherent caches and support a simplified
* flushing procedure. See
* POWER9 UM, 4.6.2.2 Instruction Cache Block Invalidate (icbi)
* https://ibm.ent.box.com/s/tmklq90ze7aj8f4n32er1mu3sy9u8k3k
*/
if (have_coherent_icache) {
asm volatile ("sync\n\t"
"icbi 0,%0\n\t"
"isync"
: : "r"(rx) : "memory");
return;
}
dsize = qemu_dcache_linesize;
isize = qemu_icache_linesize;
b = rw & ~(dsize - 1);
e = (rw + len + dsize - 1) & ~(dsize - 1);