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From: | LIU Zhiwei |
Subject: | Re: [PATCH] target/riscv: pmp: Fixup TLB size calculation |
Date: | Wed, 12 Oct 2022 14:04:25 +0800 |
User-agent: | Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.3.2 |
On 2022/10/12 11:09, Alistair Francis wrote:
On Wed, Oct 12, 2022 at 12:50 PM LIU Zhiwei <zhiwei_liu@linux.alibaba.com> wrote:Reviewed-by: LIU Zhiwei<zhiwei_liu@linux.alibaba.com>Thanks!By the way, we missed one related patch that once had been picked to riscv-next patch. The patch v3: https://lore.kernel.org/all/ceeb4037-6d17-0a09-f35a-eaf3280339bb@c-sky.com/T/#m183e4430bda408bc3a2b2751aa94eff7fc02e23cSo this was applied but caused boot failures so it was dropped from my RISC-V treeThe patch v4: https://lists.gnu.org/archive/html/qemu-devel/2021-12/msg02854.htmlI think I misunderstood this comment [1] as applying to v4 and it never got applied. Do you mind resending the patch?
Sure. I haveĀ rebased it to your patch and sent it to the mail list. Thanks, Zhiwei
1: https://lore.kernel.org/all/ceeb4037-6d17-0a09-f35a-eaf3280339bb@c-sky.com/T/#m5e958d702d9905169a941f2ae59fdf7ac4a02383 AlistairI think the patch v4 should be taken at the same time with this patch. Thanks, Zhiwei On 2022/10/12 9:14, Alistair Francis wrote:From: Alistair Francis <alistair.francis@wdc.com> Since commit 4047368938f6 "accel/tcg: Introduce tlb_set_page_full" we have been seeing this assert ../accel/tcg/cputlb.c:1294: tlb_set_page_with_attrs: Assertion `is_power_of_2(size)' failed. When running Tock on the OpenTitan machine. The issue is that pmp_get_tlb_size() would return a TLB size that wasn't a power of 2. The size was also smaller then TARGET_PAGE_SIZE. This patch ensures that any TLB size less then TARGET_PAGE_SIZE is rounded down to 1 to ensure it's a valid size. Signed-off-by: Alistair Francis <alistair.francis@wdc.com> --- This is based on advice from Richard: https://patchwork.kernel.org/project/qemu-devel/patch/20221004141051.110653-9-richard.henderson@linaro.org/#25043166 target/riscv/pmp.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c index ea2b67d947..2b43e399b8 100644 --- a/target/riscv/pmp.c +++ b/target/riscv/pmp.c @@ -628,6 +628,18 @@ bool pmp_is_range_in_tlb(CPURISCVState *env, hwaddr tlb_sa, } if (*tlb_size != 0) { + /* + * At this point we have a tlb_size that is the smallest possible size + * That fits within a TARGET_PAGE_SIZE and the PMP region. + * + * If the size is less then TARGET_PAGE_SIZE we drop the size to 1. + * This means the result isn't cached in the TLB and is only used for + * a single translation. + */ + if (*tlb_size < TARGET_PAGE_SIZE) { + *tlb_size = 1; + } + return true; }
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