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[109.243.64.38]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-55b88c9931bsm278746e87.101.2025.07.31.08.58.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 31 Jul 2025 08:58:48 -0700 (PDT) X-Outflank-Mailman: Message body and most headers restored to incoming version 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: 3fbad327-6e27-11f0-b895-0df219b8e170 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1753977529; x=1754582329; 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=StTBO6QPLNBjKleSGjDNqc33RY5wJ7PjLuBf0sj/FWM=; b=LVR7NiMbmoAwkTBfz6lKXP2OfexGvgAvxRIIqe2c9s8eyTX9OvN9ts/bqBHd4IVX0m +Hfv4SCY8fecb4QDEc2Hc6Ig0GxVI0e63TkijLVC2vP7FvDcIwQfd5T1wkpL6g67dqyA edYVVYxmzKk2oqEtAuZrvJAi828DnIfnkRT812hoGHPxka5F2Wu+LXoLc3gTl3KJvl3s BckPl7acusUI6eOkPMUNUc+aCAait+CJXhACidBWHTqM/lcWl9KOx8XSD4diSQq4JFxH 3DUx1UV3K5BQ8fjSKtZNT8UVKm/VszVqTzSXutd7ETTM54IMhSBM8u4tLRKaC7kUj2/4 2QWg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1753977529; x=1754582329; 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=StTBO6QPLNBjKleSGjDNqc33RY5wJ7PjLuBf0sj/FWM=; b=ELXB35eY8Mnz8xdXtPXVoFSEcek5Cmuh2cYk/cx+odsxxCwf73z8UYdgnL8Ir5lPXs sz1bDfv4OsII06OMNGt2wnfbBUACI7pt1Yeyrmn5cFjQ+VJTeAEBJu6AqxqoOaj6JWbH 1WusH61OtTVu6kcZo1b3P+BvIOHRvy8RaR83ZwJnDb63J3El08IjEXd4vEvFC0CGiJxy EeXK+PtT630+FUsq2Vfdx7N1V2U9OG8/06h3mL5BQLx7w3Q15nr/e8iUtFj8ryh7T39D gCajqC0Kz/gXQaaWxHlUiC9irHVwWwLF6yn+EWJDzq4HN5WNOda1oOU7r4/XuKgab887 5sWg== X-Gm-Message-State: AOJu0YxtM+j6YyleHUDhQHonXlKycY8566He834XovsN20BGM4/1jn0J hyWigRXMevkMkwmxl5/nL0PnS1D2KLiEGW1PQqihiWWpcRpSaohisrNbn5XCCg== X-Gm-Gg: ASbGncvRVmcRXpnUhw1Xwy/shUyhjGuSt3g8BbYEMM27873sKxWTfJBlsVp2nf5lToe pSF/WtKIf0tFmCqSRx6UIogqkXuu2GNj/lRNMTEP6pgHXqJysBbjn97+mEkF+VLoJDuyA5iR4Vw jo6a3TK0Ek9QMnNX9U7w6qd1PITlVKYL5q4rL+FuG7CYQT+pVdKX55/SG0Gd9L0uP5jopc3QeQv sg0lc8cmYNjusMnPv+XoMf7heRmp2K2ROJthkcLz3PvCy3lg31VufNVBs2Lr/P/bipT/hUvBPBp cwVEe7R0gNgydUtSv9gjMvbsENMEA8hHd/D7rhEVRwIJZIn7/T8ORwjdI9C7MDVnRnUd9gvNRIX f40yaWs1qiGYXuYT0L+NdlHEcxL0GV1+XoeK2s/5+fj/gUfZdRLDjcZpAz89h9eBQ4mDa/oX7 X-Google-Smtp-Source: AGHT+IFPZNBVWzDAkCO16wEd9+4o4LZMpnG6Ew5Mfti5hJlpZGh0FHkTWJfx8oFmIsWfmGud0tXF9Q== X-Received: by 2002:a05:6512:a95:b0:553:510d:f46b with SMTP id 2adb3069b0e04-55b7c071824mr3451131e87.32.1753977529096; Thu, 31 Jul 2025 08:58:49 -0700 (PDT) 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=20Pau=20Monn=C3=A9?= , Stefano Stabellini Subject: [PATCH v3 13/20] xen/riscv: Implement p2m_free_subtree() and related helpers Date: Thu, 31 Jul 2025 17:58:12 +0200 Message-ID: <41845723a7b0e3efd09095d13e57aace6f7747ef.1753973161.git.oleksii.kurochko@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @gmail.com) X-ZM-MESSAGEID: 1753977668466116600 This patch introduces a working implementation of p2m_free_subtree() for RI= SC-V based on ARM's implementation of p2m_free_entry(), enabling proper cleanup of page table entries in the P2M (physical-to-machine) mapping. Only few things are changed: - Introduce and use p2m_get_type() to get a type of p2m entry as RISC-V's PTE doesn't have enough space to store all necessary types so a type is stored outside PTE. But, at the moment, handle only types which fit into PTE's bits. Key additions include: - p2m_free_subtree(): Recursively frees page table entries at all levels. It handles both regular and superpage mappings and ensures that TLB entries are flushed before freeing intermediate tables. - p2m_put_page() and helpers: - p2m_put_4k_page(): Clears GFN from xenheap pages if applicable. - p2m_put_2m_superpage(): Releases foreign page references in a 2MB superpage. - p2m_get_type(): Extracts the stored p2m_type from the PTE bits. - p2m_free_page(): Returns a page to a domain's freelist. - Introduce p2m_is_foreign() and connected to it things. Defines XEN_PT_ENTRIES in asm/page.h to simplify loops over page table entries. Signed-off-by: Oleksii Kurochko --- Changes in V3: - Use p2m_tlb_flush_sync(p2m) instead of p2m_force_tlb_flush_sync() in p2m_free_subtree(). - Drop p2m_is_valid() implementation as pte_is_valid() is going to be used instead. - Drop p2m_is_superpage() and introduce pte_is_superpage() instead. - s/p2m_free_entry/p2m_free_subtree. - s/p2m_type_radix_get/p2m_get_type. - Update implementation of p2m_get_type() to get type both from PTE bits, other cases will be covered in a separate patch. This requires an introduction of new P2M_TYPE_PTE_BITS_MASK macros. - Drop p2m argument of p2m_get_type() as it isn't needed anymore. - Put cheapest checks first in p2m_is_superpage(). - Use switch() in p2m_put_page(). - Update the comment in p2m_put_foreign_page(). - Code style fixes. - Move p2m_foreign stuff to this commit. - Drop p2m argument of p2m_put_page() as itsn't used anymore. --- Changes in V2: - New patch. It was a part of 2ma big patch "xen/riscv: implement p2m mapp= ing functionality" which was splitted to smaller. - s/p2m_is_superpage/p2me_is_superpage. --- xen/arch/riscv/include/asm/p2m.h | 18 +++- xen/arch/riscv/include/asm/page.h | 6 ++ xen/arch/riscv/include/asm/paging.h | 2 + xen/arch/riscv/p2m.c | 137 +++++++++++++++++++++++++++- xen/arch/riscv/paging.c | 7 ++ 5 files changed, 168 insertions(+), 2 deletions(-) diff --git a/xen/arch/riscv/include/asm/p2m.h b/xen/arch/riscv/include/asm/= p2m.h index 26ad87b8df..fbc73448a7 100644 --- a/xen/arch/riscv/include/asm/p2m.h +++ b/xen/arch/riscv/include/asm/p2m.h @@ -79,10 +79,20 @@ typedef enum { p2m_ext_storage, /* Following types'll be stored outsude PTE bits: = */ p2m_grant_map_rw, /* Read/write grant mapping */ p2m_grant_map_ro, /* Read-only grant mapping */ + p2m_map_foreign_rw, /* Read/write RAM pages from foreign domain */ + p2m_map_foreign_ro, /* Read-only RAM pages from foreign domain */ } p2m_type_t; =20 #define p2m_mmio_direct p2m_mmio_direct_io =20 +/* + * Bits 8 and 9 are reserved for use by supervisor software; + * the implementation shall ignore this field. + * We are going to use to save in these bits frequently used types to avoid + * get/set of a type from radix tree. + */ +#define P2M_TYPE_PTE_BITS_MASK 0x300 + /* We use bitmaps and mask to handle groups of types */ #define p2m_to_mask(t_) BIT(t_, UL) =20 @@ -93,10 +103,16 @@ typedef enum { #define P2M_GRANT_TYPES (p2m_to_mask(p2m_grant_map_rw) | \ p2m_to_mask(p2m_grant_map_ro)) =20 + /* Foreign mappings types */ +#define P2M_FOREIGN_TYPES (p2m_to_mask(p2m_map_foreign_rw) | \ + p2m_to_mask(p2m_map_foreign_ro)) + /* Useful predicates */ #define p2m_is_ram(t_) (p2m_to_mask(t_) & P2M_RAM_TYPES) #define p2m_is_any_ram(t_) (p2m_to_mask(t_) & \ - (P2M_RAM_TYPES | P2M_GRANT_TYPES)) + (P2M_RAM_TYPES | P2M_GRANT_TYPES | \ + P2M_FOREIGN_TYPES)) +#define p2m_is_foreign(t_) (p2m_to_mask(t_) & P2M_FOREIGN_TYPES) =20 #include =20 diff --git a/xen/arch/riscv/include/asm/page.h b/xen/arch/riscv/include/asm= /page.h index 66cb192316..cb303af0c0 100644 --- a/xen/arch/riscv/include/asm/page.h +++ b/xen/arch/riscv/include/asm/page.h @@ -20,6 +20,7 @@ #define XEN_PT_LEVEL_SIZE(lvl) (_AT(paddr_t, 1) << XEN_PT_LEVEL_SHIFT= (lvl)) #define XEN_PT_LEVEL_MAP_MASK(lvl) (~(XEN_PT_LEVEL_SIZE(lvl) - 1)) #define XEN_PT_LEVEL_MASK(lvl) (VPN_MASK << XEN_PT_LEVEL_SHIFT(lvl)) +#define XEN_PT_ENTRIES (_AT(unsigned int, 1) << PAGETABLE_ORD= ER) =20 /* * PTE format: @@ -182,6 +183,11 @@ static inline bool pte_is_mapping(pte_t p) return (p.pte & PTE_VALID) && (p.pte & PTE_ACCESS_MASK); } =20 +static inline bool pte_is_superpage(pte_t p, unsigned int level) +{ + return (level > 0) && pte_is_mapping(p); +} + static inline int clean_and_invalidate_dcache_va_range(const void *p, unsigned long size) { diff --git a/xen/arch/riscv/include/asm/paging.h b/xen/arch/riscv/include/a= sm/paging.h index 557fbd1abc..c9063b7f76 100644 --- a/xen/arch/riscv/include/asm/paging.h +++ b/xen/arch/riscv/include/asm/paging.h @@ -12,4 +12,6 @@ int paging_freelist_init(struct domain *d, unsigned long = pages, =20 bool paging_ret_pages_to_domheap(struct domain *d, unsigned int nr_pages); =20 +void paging_free_page(struct domain *d, struct page_info *pg); + #endif /* ASM_RISCV_PAGING_H */ diff --git a/xen/arch/riscv/p2m.c b/xen/arch/riscv/p2m.c index 6c99719c66..2467e459cc 100644 --- a/xen/arch/riscv/p2m.c +++ b/xen/arch/riscv/p2m.c @@ -197,6 +197,16 @@ static pte_t *p2m_get_root_pointer(struct p2m_domain *= p2m, gfn_t gfn) return __map_domain_page(p2m->root + root_table_indx); } =20 +static p2m_type_t p2m_get_type(const pte_t pte) +{ + p2m_type_t type =3D MASK_EXTR(pte.pte, P2M_TYPE_PTE_BITS_MASK); + + if ( type =3D=3D p2m_ext_storage ) + panic("unimplemented\n"); + + return type; +} + static inline void p2m_write_pte(pte_t *p, pte_t pte, bool clean_pte) { write_pte(p, pte); @@ -248,11 +258,136 @@ static int p2m_next_level(struct p2m_domain *p2m, bo= ol alloc_tbl, return P2M_TABLE_MAP_NONE; } =20 +static void p2m_put_foreign_page(struct page_info *pg) +{ + /* + * It=E2=80=99s safe to call put_page() here because arch_flush_tlb_ma= sk() + * will be invoked if the page is reallocated before the end of + * this loop, which will trigger a flush of the guest TLBs. + */ + put_page(pg); +} + +/* Put any references on the single 4K page referenced by mfn. */ +static void p2m_put_4k_page(mfn_t mfn, p2m_type_t type) +{ + /* TODO: Handle other p2m types */ + + if ( p2m_is_foreign(type) ) + { + ASSERT(mfn_valid(mfn)); + p2m_put_foreign_page(mfn_to_page(mfn)); + } + + /* + * Detect the xenheap page and mark the stored GFN as invalid. + * We don't free the underlying page until the guest requested to do s= o. + * So we only need to tell the page is not mapped anymore in the P2M by + * marking the stored GFN as invalid. + */ + if ( p2m_is_ram(type) && is_xen_heap_mfn(mfn) ) + page_set_xenheap_gfn(mfn_to_page(mfn), INVALID_GFN); +} + +/* Put any references on the superpage referenced by mfn. */ +static void p2m_put_2m_superpage(mfn_t mfn, p2m_type_t type) +{ + struct page_info *pg; + unsigned int i; + + ASSERT(mfn_valid(mfn)); + + pg =3D mfn_to_page(mfn); + + for ( i =3D 0; i < XEN_PT_ENTRIES; i++, pg++ ) + p2m_put_foreign_page(pg); +} + +/* Put any references on the page referenced by pte. */ +static void p2m_put_page(const pte_t pte, unsigned int level) +{ + mfn_t mfn =3D pte_get_mfn(pte); + p2m_type_t p2m_type =3D p2m_get_type(pte); + + ASSERT(pte_is_valid(pte)); + + /* + * TODO: Currently we don't handle level 2 super-page, Xen is not + * preemptible and therefore some work is needed to handle such + * superpages, for which at some point Xen might end up freeing memory + * and therefore for such a big mapping it could end up in a very long + * operation. + */ + switch ( level ) + { + case 1: + return p2m_put_2m_superpage(mfn, p2m_type); + + case 0: + return p2m_put_4k_page(mfn, p2m_type); + } +} + +static void p2m_free_page(struct p2m_domain *p2m, struct page_info *pg) +{ + page_list_del(pg, &p2m->pages); + + paging_free_page(p2m->domain, pg); +} + /* Free pte sub-tree behind an entry */ static void p2m_free_subtree(struct p2m_domain *p2m, pte_t entry, unsigned int level) { - panic("%s: hasn't been implemented yet\n", __func__); + unsigned int i; + pte_t *table; + mfn_t mfn; + struct page_info *pg; + + /* Nothing to do if the entry is invalid. */ + if ( !pte_is_valid(entry) ) + return; + + if ( pte_is_superpage(entry, level) || (level =3D=3D 0) ) + { +#ifdef CONFIG_IOREQ_SERVER + /* + * If this gets called then either the entry was replaced by an en= try + * with a different base (valid case) or the shattering of a super= page + * has failed (error case). + * So, at worst, the spurious mapcache invalidation might be sent. + */ + if ( p2m_is_ram(p2m_get_type(p2m, entry)) && + domain_has_ioreq_server(p2m->domain) ) + ioreq_request_mapcache_invalidate(p2m->domain); +#endif + + p2m_put_page(entry, level); + + return; + } + + table =3D map_domain_page(pte_get_mfn(entry)); + for ( i =3D 0; i < XEN_PT_ENTRIES; i++ ) + p2m_free_subtree(p2m, table[i], level - 1); + + unmap_domain_page(table); + + /* + * Make sure all the references in the TLB have been removed before + * freing the intermediate page table. + * XXX: Should we defer the free of the page table to avoid the + * flush? + */ + p2m_tlb_flush_sync(p2m); + + mfn =3D pte_get_mfn(entry); + ASSERT(mfn_valid(mfn)); + + pg =3D mfn_to_page(mfn); + + page_list_del(pg, &p2m->pages); + p2m_free_page(p2m, pg); } =20 /* diff --git a/xen/arch/riscv/paging.c b/xen/arch/riscv/paging.c index bbe1186900..853e0e14c6 100644 --- a/xen/arch/riscv/paging.c +++ b/xen/arch/riscv/paging.c @@ -84,6 +84,13 @@ bool paging_ret_pages_to_domheap(struct domain *d, unsig= ned int nr_pages) return true; } =20 +void paging_free_page(struct domain *d, struct page_info *pg) +{ + spin_lock(&d->arch.paging.lock); + page_list_add_tail(pg, &d->arch.paging.freelist); + spin_unlock(&d->arch.paging.lock); +} + /* Domain paging struct initialization. */ int paging_domain_init(struct domain *d) { --=20 2.50.1