From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 7D71EA42 for ; Thu, 8 Jun 2023 01:31:27 +0000 (UTC) Received: from loongson.cn (unknown [10.180.13.185]) by gateway (Coremail) with SMTP id _____8DxzOptL4Fk_k4AAA--.1190S3; Thu, 08 Jun 2023 09:31:25 +0800 (CST) Received: from [10.180.13.185] (unknown [10.180.13.185]) by localhost.localdomain (Coremail) with SMTP id AQAAf8CxCOVsL4Fk2SYGAA--.20258S3; Thu, 08 Jun 2023 09:31:24 +0800 (CST) Subject: Re: Re: [PATCH] LoongArch: let pmd_present return true when splitting pmd To: "bibo, mao" , Huacai Chen , WANG Xuerui , Andrew Morton , Anshuman Khandual , David Hildenbrand , Mike Rapoport , Jiaxun Yang , Feiyang Chen , Qi Zheng Cc: loongson-kernel@lists.loongnix.cn, loongarch@lists.linux.dev, linux-kernel@vger.kernel.org References: <20230524074132.10916-1-zhanghongchen@loongson.cn> <46ce41a3-16bd-6d92-c8a8-764283859190@loongson.cn> From: Hongchen Zhang Message-ID: Date: Thu, 8 Jun 2023 09:31:24 +0800 User-Agent: Mozilla/5.0 (X11; Linux loongarch64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 Precedence: bulk X-Mailing-List: loongarch@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-CM-TRANSID:AQAAf8CxCOVsL4Fk2SYGAA--.20258S3 X-CM-SenderInfo: x2kd0w5krqwupkhqwqxorr0wxvrqhubq/1tbiAQAPB2R-IgAHlgACsj X-Coremail-Antispam: 1Uk129KBj93XoWxuF1rAFWxJw18GrWUCw47WrX_yoWrGry3p3 Z7CFyrCrW5KFn3C34UtFy3XryUArsrG3Wqqr98GF18JFW7X3s2qrn8Wr909ry8Xan5try8 Xr45Ww15uFy3JwbCm3ZEXasCq-sJn29KB7ZKAUJUUUU7529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUPFb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1Y6r17M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVWxJVW8Jr1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6r4j6r4UJwAaw2AFwI0_Jrv_JF1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqjxCEc2xF0c Ia020Ex4CE44I27wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_JF0_ Jw1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvEwIxGrw CYjI0SjxkI62AI1cAE67vIY487MxkF7I0En4kS14v26r126r1DMxAIw28IcxkI7VAKI48J MxC20s026xCaFVCjc4AY6r1j6r4UMxCIbckI1I0E14v26r1Y6r17MI8I3I0E5I8CrVAFwI 0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y 0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxV WUJVW8JwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1l IxAIcVC2z280aVCY1x0267AKxVWUJVW8JbIYCTnIWIevJa73UjIFyTuYvjxUcpBTUUUUU Hi Bibo & Anshuman, On 2023/6/6 下午9:49, bibo, mao wrote: > I do not object to adding sw bit for _PAGE_PRESENT_INVALID, only that can it use > bit12--bit20 since it is for pmd entry only? If we change from bit60 to bit12, pmd_pfn will return an incorrect pfn, and it seems that modifying pmd_pfn accordingly is not a good idea. Hi Anshuman, What's your opinion about this suggestion? I think arm64 architecture has similar problems. Why do you choose bit59 instead of bit12--bit20? > > Regards > Bibo, Mao > > 在 2023/6/6 19:38, Hongchen Zhang 写道: >> Hi, >> >> Gentle ping. >> >> On 2023/5/24 pm 3:41, Hongchen Zhang wrote: >>> when we split a pmd into ptes, pmd_present() and pmd_trans_huge() should >>> return true,otherwise it would be treated as a swap pmd. >>> As arm64 does in >>> commit b65399f6111b ("arm64/mm: Change THP helpers to comply with generic MM semantics") >>> we add a _PAGE_PRESENT_INVALID bit for LoongArch. >>> >>> Signed-off-by: Hongchen Zhang >>> --- >>>   arch/loongarch/include/asm/pgtable-bits.h | 2 ++ >>>   arch/loongarch/include/asm/pgtable.h      | 3 ++- >>>   2 files changed, 4 insertions(+), 1 deletion(-) >>> >>> diff --git a/arch/loongarch/include/asm/pgtable-bits.h b/arch/loongarch/include/asm/pgtable-bits.h >>> index 8b98d22a145b..a7469d28d9d0 100644 >>> --- a/arch/loongarch/include/asm/pgtable-bits.h >>> +++ b/arch/loongarch/include/asm/pgtable-bits.h >>> @@ -22,12 +22,14 @@ >>>   #define    _PAGE_PFN_SHIFT        12 >>>   #define    _PAGE_SWP_EXCLUSIVE_SHIFT 23 >>>   #define    _PAGE_PFN_END_SHIFT    48 >>> +#define _PAGE_PRESENT_INVALID_SHIFT 60 >>>   #define    _PAGE_NO_READ_SHIFT    61 >>>   #define    _PAGE_NO_EXEC_SHIFT    62 >>>   #define    _PAGE_RPLV_SHIFT    63 >>>     /* Used by software */ >>>   #define _PAGE_PRESENT        (_ULCAST_(1) << _PAGE_PRESENT_SHIFT) >>> +#define _PAGE_PRESENT_INVALID    (_ULCAST_(1) << _PAGE_PRESENT_INVALID_SHIFT) >>>   #define _PAGE_WRITE        (_ULCAST_(1) << _PAGE_WRITE_SHIFT) >>>   #define _PAGE_ACCESSED        (_ULCAST_(1) << _PAGE_ACCESSED_SHIFT) >>>   #define _PAGE_MODIFIED        (_ULCAST_(1) << _PAGE_MODIFIED_SHIFT) >>> diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h >>> index d28fb9dbec59..9a9f9ff9b709 100644 >>> --- a/arch/loongarch/include/asm/pgtable.h >>> +++ b/arch/loongarch/include/asm/pgtable.h >>> @@ -213,7 +213,7 @@ static inline int pmd_bad(pmd_t pmd) >>>   static inline int pmd_present(pmd_t pmd) >>>   { >>>       if (unlikely(pmd_val(pmd) & _PAGE_HUGE)) >>> -        return !!(pmd_val(pmd) & (_PAGE_PRESENT | _PAGE_PROTNONE)); >>> +        return !!(pmd_val(pmd) & (_PAGE_PRESENT | _PAGE_PROTNONE | _PAGE_PRESENT_INVALID)); >>>         return pmd_val(pmd) != (unsigned long)invalid_pte_table; >>>   } >>> @@ -558,6 +558,7 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) >>>     static inline pmd_t pmd_mkinvalid(pmd_t pmd) >>>   { >>> +    pmd_val(pmd) |= _PAGE_PRESENT_INVALID; >>>       pmd_val(pmd) &= ~(_PAGE_PRESENT | _PAGE_VALID | _PAGE_DIRTY | _PAGE_PROTNONE); >>>         return pmd; >>> >>> base-commit: f1fcbaa18b28dec10281551dfe6ed3a3ed80e3d6 >>> >> >> Best Regards >> Hongchen Zhang >> >> _______________________________________________ >> Loongson-kernel mailing list -- loongson-kernel@lists.loongnix.cn >> To unsubscribe send an email to loongson-kernel-leave@lists.loongnix.cn > >