[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH] accel/tcg: Consider cluster index in tb_lookup_
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH] accel/tcg: Consider cluster index in tb_lookup__cpu_state() |
Date: |
Wed, 6 Feb 2019 03:15:26 +0000 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 |
On 2/5/19 3:18 PM, Peter Maydell wrote:
> In commit f7b78602fdc6c6e4be we added the CPU cluster number to the
> cflags field of the TB hash; this included adding it to the value
> kept in tb->cflags, since we pass that field directly into the hash
> calculation in some places. Unfortunately we forgot to check whether
> other parts of the code were doing comparisons against tb->cflags
> that would need to be updated.
>
> It turns out that there is exactly one such place: the
> tb_lookup__cpu_state() function checks whether the TB it has
> found in the tb_jmp_cache has a tb->cflags matching the cf_mask
> that is passed in. The tb->cflags has the cluster_index in it
> but the cf_mask does not.
>
> Hoist the "add cluster index to the cf_mask" code up from
> tb_htable_lookup() to tb_lookup__cpu_state() so it can be considered
> in the "did this TB match in the jmp cache" condition, as well as
> when we do the full hash lookup by physical PC, flags, etc.
> (tb_htable_lookup() is only called from tb_lookup__cpu_state(),
> so this change doesn't require any further knock-on changes.)
>
> Fixes: f7b78602fdc6c6e4be ("accel/tcg: Add cluster number to TCG TB hash")
> Reported-by: Howard Spoelstra <address@hidden>
> Reported-by: Cleber Rosa <address@hidden>
> Signed-off-by: Peter Maydell <address@hidden>
Reviewed-by: Richard Henderson <address@hidden>
> Does anybody know why tb_lookup__cpu_state() has that odd
> double-underscore in the middle of its name?
I'm inclined to think typo... Emilio?
r~