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[90.112.153.108]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38c5c1b574fsm12737179f8f.70.2025.02.03.05.12.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Feb 2025 05:12:12 -0800 (PST) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 7c4cc656-e230-11ef-a0e7-8be0dac302b0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1738588333; x=1739193133; darn=lists.xenproject.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=LiBe5bsV0kJrh/WNv5u+VjlusqPfI3FOI2X11zbF91U=; b=f4z0X7dgU2/oEGAszkGg348UxFgWf8NKRpbVQOk0/2oUan9u7nNBy6UTYT9KOsDcm3 SG5uj4ftlK8gI227gRF8j5NiTt93tBIRXPIHsSL7N47uqcbT1tbIzG720Tt+Y7VBVjyT wetx2vWINdm5wZNVxnY203Y1AStBu0Y/kCgXtf5kcPzwVrLhCDdu9r0hqFBoJ4F2szgW mgiB6clCYAYoJFB3i4zPW7SVr/mdNxDC7N1Cix+yBVU3lcsXzVbmLRUldzrPW5VfftXf 8MZn4bQRzbbw6LvyBFADRpP6F0d3vuMz+ScmsN12pyHWIxYhcHY/7cE2uusyqyF1NPnG Mcdg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1738588333; x=1739193133; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=LiBe5bsV0kJrh/WNv5u+VjlusqPfI3FOI2X11zbF91U=; b=Mw8ACAxQ+VuQPXpomZANnR86jG0S/L1wK0nL1HiOeUSdvkFFCE/WKHMroK0yA+M/rF 8gKy72ozrNHw3ZmRUxpD3ZVR7DsSRSybOOtX0SexjgVvS9UzdUMU7fa+M8wdXutVoEBF EqKFMm4pQJ+WBFcF5wkm0iaRmILR1E6ebtssE04Zbp0qPYjWeF6u8pGxVyw8Us5Xfdc3 WpythTJYZlyi/aTcZWQib78GziYm63LrcojIsq//ZloDgNav6mfhHExVjCXgukXuhQNv DFSRrJs9HJMm0aTC3n12bjblHsrZYzHVyHpveLHrvNIBqlmswHkGJ3xqKbkEmZ6R/AAJ Q7Rg== X-Gm-Message-State: AOJu0YyGrqKbTa8RZOMePjuhHvKl9Tb/yuAzjTYfPtLV8jY5ie87zsbn 4a/MNz+XheVXe6GkUDGOCN1R14Yf/036/lYTbr7LZuABLdYtTWefICNMSjyr X-Gm-Gg: ASbGncvKzC8CdtdmaMRIeGXaEm1J+EFYRsQfMoweFsro9VnQXonmhA8qKHc2QpARQ4d 3kHHCbVpJrPKkcHwxJyFxuXIVH/o77sNcNpv3T8Z6ODmZO9zoMvK8CiTysdrS3GHl1tl2fWTK2X EsmrZBbbCRwYf4ORevipGkZWOvk6p9WAopmAIqcGUss7PHNrokzLwCFZxa7ONrg4aKxgMK8nnrs PNBO1XMODAbzd/wxj75Vd/KIzI6yVJyhge4xu5ewunP9XZcMnzX4OrdZyJ3Yu1PrlIjwAO0AXsX zpiBKPJR0DNgcaj9RZS0qnFgqk+E82ckK+4MRUCO5P+lbx4bn3HK7L65uTMI6MQiG1PYtoKFsc3 6V2mDRx8V X-Google-Smtp-Source: AGHT+IFl2kNLx1m7MWY3jGR2rzn7IL/xF8DWl0CL1yD1hQ3UQvASIepy8MlJF2V6sPF7gPybVE5q8A== X-Received: by 2002:a5d:6d02:0:b0:385:f560:7924 with SMTP id ffacd0b85a97d-38c5194d0b6mr15342408f8f.4.1738588333047; Mon, 03 Feb 2025 05:12:13 -0800 (PST) From: Oleksii Kurochko To: xen-devel@lists.xenproject.org Cc: Oleksii Kurochko , Alistair Francis , Bob Eshleman , Connor Davis , Andrew Cooper , Anthony PERARD , Michal Orzel , Jan Beulich , Julien Grall , =?utf-8?q?Roger_Pau_Monn=C3=A9?= , Stefano Stabellini Subject: [PATCH v2 for 4.20? 1/3] xen/riscv: implement software page table walking Date: Mon, 3 Feb 2025 14:12:02 +0100 Message-ID: X-Mailer: git-send-email 2.48.1 In-Reply-To: References: MIME-Version: 1.0 RISC-V doesn't have hardware feature to ask MMU to translate virtual address to physical address ( like Arm has, for example ), so software page table walking is implemented. As pte_walk() returns pte_t and it requires inclusion of in , the following compilation started to occur after this inclusion: - implicit declaration of function 'GENMASK'. To resolve this, needs to be included at the top of . - implicit declaration of map_domain_page() and unmap_domain_page(). This issue arises because, after including in , we could have the following hierarchy if someone decides to include : ... flush_to_ram() which uses {un}map_domain_page() <--- ... Declaration of {un}map_domain_page() happens here <--- To avoid this compilation issue, definition of flush_to_ram() is moved to mm.c. Signed-off-by: Oleksii Kurochko --- Changes in v2: - Update the code of pt_walk() to return pte_t instead of paddr_t. - Fix typos and drop blankets inside parentheses in the comment. - Update the `ret` handling; there is no need for `mfn` calculation anymore as pt_walk() returns or pte_t of a leaf node or non-present pte_t. - Drop the comment before unmap_table(). - Drop local variable `pa` as pt_walk() is going to return pte_t instead of paddr_t. - Add the comment above pt_walk() to explain what it does and returns. - Add additional explanation about possible return values of pt_next_level() used inside while loop in pt_walk(). - Change `pa` to `table` in the comment before while loop in pt_walk() as actually this loop finds a page table where paga table entry for `va` is located. - After including in , the following compilation error occurs: ./arch/riscv/include/asm/cmpxchg.h:56:9: error: implicit declaration of function 'GENMASK' To resolve this, needs to be included at the top of . - To avoid an issue with the implicit declaration of map_domain_page() and unmap_domain_page() after including in , the implementation of flush_page_to_ram() has been moved to mm.c. (look for more detailed explanation in the commit message) As a result drop inclusion of in . - Update the commit message --- xen/arch/riscv/include/asm/cmpxchg.h | 1 + xen/arch/riscv/include/asm/mm.h | 4 ++ xen/arch/riscv/include/asm/page.h | 14 +------ xen/arch/riscv/mm.c | 14 +++++++ xen/arch/riscv/pt.c | 55 ++++++++++++++++++++++++++++ 5 files changed, 75 insertions(+), 13 deletions(-) diff --git a/xen/arch/riscv/include/asm/cmpxchg.h b/xen/arch/riscv/include/asm/cmpxchg.h index 662d3fd5d4..4cfe5927b7 100644 --- a/xen/arch/riscv/include/asm/cmpxchg.h +++ b/xen/arch/riscv/include/asm/cmpxchg.h @@ -4,6 +4,7 @@ #ifndef ASM__RISCV__CMPXCHG_H #define ASM__RISCV__CMPXCHG_H +#include #include #include diff --git a/xen/arch/riscv/include/asm/mm.h b/xen/arch/riscv/include/asm/mm.h index 292aa48fc1..10a15a8b03 100644 --- a/xen/arch/riscv/include/asm/mm.h +++ b/xen/arch/riscv/include/asm/mm.h @@ -156,6 +156,10 @@ static inline struct page_info *virt_to_page(const void *v) return frametable_virt_start + PFN_DOWN(va - directmap_virt_start); } +#include + +pte_t * pt_walk(vaddr_t va, unsigned int *pte_level); + /* * Common code requires get_page_type and put_page_type. * We don't care about typecounts so we just do the minimum to make it diff --git a/xen/arch/riscv/include/asm/page.h b/xen/arch/riscv/include/asm/page.h index 7a6174a109..b9076173f4 100644 --- a/xen/arch/riscv/include/asm/page.h +++ b/xen/arch/riscv/include/asm/page.h @@ -7,7 +7,6 @@ #include #include -#include #include #include @@ -177,18 +176,7 @@ static inline void invalidate_icache(void) #define clear_page(page) memset((void *)(page), 0, PAGE_SIZE) #define copy_page(dp, sp) memcpy(dp, sp, PAGE_SIZE) -static inline void flush_page_to_ram(unsigned long mfn, bool sync_icache) -{ - const void *v = map_domain_page(_mfn(mfn)); - - if ( clean_and_invalidate_dcache_va_range(v, PAGE_SIZE) ) - BUG(); - - unmap_domain_page(v); - - if ( sync_icache ) - invalidate_icache(); -} +void flush_page_to_ram(unsigned long mfn, bool sync_icache); /* Write a pagetable entry. */ static inline void write_pte(pte_t *p, pte_t pte) diff --git a/xen/arch/riscv/mm.c b/xen/arch/riscv/mm.c index f2bf279bac..32574c879b 100644 --- a/xen/arch/riscv/mm.c +++ b/xen/arch/riscv/mm.c @@ -3,6 +3,7 @@ #include #include #include +#include #include #include #include @@ -564,3 +565,16 @@ void *__init arch_vmap_virt_end(void) { return (void *)(VMAP_VIRT_START + VMAP_VIRT_SIZE); } + +void flush_page_to_ram(unsigned long mfn, bool sync_icache) +{ + const void *v = map_domain_page(_mfn(mfn)); + + if ( clean_and_invalidate_dcache_va_range(v, PAGE_SIZE) ) + BUG(); + + unmap_domain_page(v); + + if ( sync_icache ) + invalidate_icache(); +} diff --git a/xen/arch/riscv/pt.c b/xen/arch/riscv/pt.c index a703e0f1bd..2a5a191a70 100644 --- a/xen/arch/riscv/pt.c +++ b/xen/arch/riscv/pt.c @@ -274,6 +274,61 @@ static int pt_update_entry(mfn_t root, vaddr_t virt, return rc; } +/* + * pt_walk() performs software page table walking and returns the pte_t of + * a leaf node or the leaf-most not-present pte_t if no leaf node is found + * for further analysis. + * Additionally, pt_walk() returns the level of the found pte. + */ +pte_t * pt_walk(vaddr_t va, unsigned int *pte_level) +{ + const mfn_t root = get_root_page(); + /* + * In pt_walk() only XEN_TABLE_MAP_NONE and XEN_TABLE_SUPER_PAGE are + * handled (as they are only possible for page table walking), so + * initialize `ret` with "impossible" XEN_TABLE_MAP_NOMEM. + */ + int ret = XEN_TABLE_MAP_NOMEM; + unsigned int level = HYP_PT_ROOT_LEVEL; + pte_t *table; + + DECLARE_OFFSETS(offsets, va); + + table = map_table(root); + + /* + * Find `table` of an entry which corresponds to `va` by iterating for each + * page level and checking if the entry points to a next page table or + * to a page. + * + * Two cases are possible: + * - ret == XEN_TABLE_SUPER_PAGE means that the entry was find; + * (Despite the name) XEN_TABLE_SUPER_PAGE also covers 4K mappings. If + * pt_next_level() is called for page table level 0, it results in the + * entry being a pointer to a leaf node, thereby returning + * XEN_TABLE_SUPER_PAGE, despite of the fact this leaf covers 4k mapping. + * - ret == XEN_TABLE_MAP_NONE means that requested `va` wasn't actually + * mapped. + */ + while ( (ret != XEN_TABLE_MAP_NONE) && (ret != XEN_TABLE_SUPER_PAGE) ) + { + /* + * This case shouldn't really occur as it will mean that for table + * level 0 a pointer to next page table has been written, but at + * level 0 it could be only a pointer to 4k page. + */ + ASSERT(level <= HYP_PT_ROOT_LEVEL); + + ret = pt_next_level(false, &table, offsets[level]); + level--; + } + + if ( pte_level ) + *pte_level = level + 1; + + return table + offsets[level + 1]; +} + /* Return the level where mapping should be done */ static int pt_mapping_level(unsigned long vfn, mfn_t mfn, unsigned long nr, unsigned int flags)