From nobody Wed Feb 11 11:28:08 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F2DFA770EF for ; Tue, 21 May 2024 11:49:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716292148; cv=none; b=gkfZ6i8JdgwCqh/TBENncSBCjo/4oO+YxuEgkwG6dXSWfm5NmHfVxUCGHxcQ+T/QkDQCRpoDL4nTnWV7kW2jVS0y1JmrlFvyCaiM73ub4wfPiL5+JCep4u2d7brN5FkmdQYpHgfdCFVdv5jwq3JvUPQ3CowLIQ8jIdP0rPJ1/kY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716292148; c=relaxed/simple; bh=YmNQGTYS7tg+RvjQBa8mIUVU0Q8jznFPplKEu6+/K8U=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=JM9ody6lixjvfbED9dEd5M+VQNF4XlMgWDJOfeo/CPIljS/WHUxdQOPFYGVt2D419kRK1/WvceY+yTgTNrxHXZKcybpP2IuJU2xAMUvANw7CnT/vp3Q5jzJyqI63SqCYQcS6/OZmGD2G2KyNW/6Ou0GzY3DelLALKYGGgRIFh0M= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UzvEzHHe; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UzvEzHHe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CC39FC2BD11; Tue, 21 May 2024 11:49:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1716292147; bh=YmNQGTYS7tg+RvjQBa8mIUVU0Q8jznFPplKEu6+/K8U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UzvEzHHexF7JresSjbUV+sseX7MhZnOt/Q6RxfcvlB4jlYBbvS+Mc5EYr2OPt3w1n VnthCTVkILvDLIi1nYESspY9tZiEk/S8GdRdvBNtYuxxGJgGKsmeVaJ4NdBI2fjNpL O4lr9BqHQjAn99ZqfKqqrd8aspSj2moxL790uHQs3eJW+b7TxXtKU8u1ydUEtbB+SJ pUsoV8TCLbwqbeD5kw7g+Jin6DjIO1XOT1XywHo8E6kMryiVfWswgG3ubvVFBby7xy B5SfqddkJ20baZ98Z3B4D3Kkq65i2wxIOluwx6t+d5EhaQjAj2Q9LikQm46I4C6dpm fz3dUdiRyl1CQ== From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= To: Alexandre Ghiti , Albert Ou , David Hildenbrand , Palmer Dabbelt , Paul Walmsley , linux-riscv@lists.infradead.org, Oscar Salvador Cc: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , Andrew Bresticker , Chethan Seshadri , Lorenzo Stoakes , Santosh Mamila , Sivakumar Munnangi , Sunil V L , linux-kernel@vger.kernel.org, linux-mm@kvack.org, virtualization@lists.linux-foundation.org Subject: [PATCH v3 5/9] riscv: mm: Add memory hotplugging support Date: Tue, 21 May 2024 13:48:26 +0200 Message-Id: <20240521114830.841660-6-bjorn@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20240521114830.841660-1-bjorn@kernel.org> References: <20240521114830.841660-1-bjorn@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Bj=C3=B6rn T=C3=B6pel For an architecture to support memory hotplugging, a couple of callbacks needs to be implemented: arch_add_memory() This callback is responsible for adding the physical memory into the direct map, and call into the memory hotplugging generic code via __add_pages() that adds the corresponding struct page entries, and updates the vmemmap mapping. arch_remove_memory() This is the inverse of the callback above. vmemmap_free() This function tears down the vmemmap mappings (if CONFIG_SPARSEMEM_VMEMMAP is enabled), and also deallocates the backing vmemmap pages. Note that for persistent memory, an alternative allocator for the backing pages can be used; The vmem_altmap. This means that when the backing pages are cleared, extra care is needed so that the correct deallocation method is used. arch_get_mappable_range() This functions returns the PA range that the direct map can map. Used by the MHP internals for sanity checks. The page table unmap/teardown functions are heavily based on code from the x86 tree. The same remove_pgd_mapping() function is used in both vmemmap_free() and arch_remove_memory(), but in the latter function the backing pages are not removed. Signed-off-by: Bj=C3=B6rn T=C3=B6pel --- arch/riscv/mm/init.c | 261 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 261 insertions(+) diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 6f72b0b2b854..6693b742bf2f 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -1493,3 +1493,264 @@ void __init pgtable_cache_init(void) } } #endif + +#ifdef CONFIG_MEMORY_HOTPLUG +static void __meminit free_pagetable(struct page *page, int order) +{ + unsigned int nr_pages =3D 1 << order; + + /* + * vmemmap/direct page tables can be reserved, if added at + * boot. + */ + if (PageReserved(page)) { + __ClearPageReserved(page); + while (nr_pages--) + free_reserved_page(page++); + return; + } + + free_pages((unsigned long)page_address(page), order); +} + +static void __meminit free_pte_table(pte_t *pte_start, pmd_t *pmd) +{ + pte_t *pte; + int i; + + for (i =3D 0; i < PTRS_PER_PTE; i++) { + pte =3D pte_start + i; + if (!pte_none(*pte)) + return; + } + + free_pagetable(pmd_page(*pmd), 0); + pmd_clear(pmd); +} + +static void __meminit free_pmd_table(pmd_t *pmd_start, pud_t *pud) +{ + pmd_t *pmd; + int i; + + for (i =3D 0; i < PTRS_PER_PMD; i++) { + pmd =3D pmd_start + i; + if (!pmd_none(*pmd)) + return; + } + + free_pagetable(pud_page(*pud), 0); + pud_clear(pud); +} + +static void __meminit free_pud_table(pud_t *pud_start, p4d_t *p4d) +{ + pud_t *pud; + int i; + + for (i =3D 0; i < PTRS_PER_PUD; i++) { + pud =3D pud_start + i; + if (!pud_none(*pud)) + return; + } + + free_pagetable(p4d_page(*p4d), 0); + p4d_clear(p4d); +} + +static void __meminit free_vmemmap_storage(struct page *page, size_t size, + struct vmem_altmap *altmap) +{ + if (altmap) + vmem_altmap_free(altmap, size >> PAGE_SHIFT); + else + free_pagetable(page, get_order(size)); +} + +static void __meminit remove_pte_mapping(pte_t *pte_base, unsigned long ad= dr, unsigned long end, + bool is_vmemmap, struct vmem_altmap *altmap) +{ + unsigned long next; + pte_t *ptep, pte; + + for (; addr < end; addr =3D next) { + next =3D (addr + PAGE_SIZE) & PAGE_MASK; + if (next > end) + next =3D end; + + ptep =3D pte_base + pte_index(addr); + pte =3D READ_ONCE(*ptep); + + if (!pte_present(*ptep)) + continue; + + pte_clear(&init_mm, addr, ptep); + if (is_vmemmap) + free_vmemmap_storage(pte_page(pte), PAGE_SIZE, altmap); + } +} + +static void __meminit remove_pmd_mapping(pmd_t *pmd_base, unsigned long ad= dr, unsigned long end, + bool is_vmemmap, struct vmem_altmap *altmap) +{ + unsigned long next; + pte_t *pte_base; + pmd_t *pmdp, pmd; + + for (; addr < end; addr =3D next) { + next =3D pmd_addr_end(addr, end); + pmdp =3D pmd_base + pmd_index(addr); + pmd =3D READ_ONCE(*pmdp); + + if (!pmd_present(pmd)) + continue; + + if (pmd_leaf(pmd)) { + pmd_clear(pmdp); + if (is_vmemmap) + free_vmemmap_storage(pmd_page(pmd), PMD_SIZE, altmap); + continue; + } + + pte_base =3D (pte_t *)pmd_page_vaddr(*pmdp); + remove_pte_mapping(pte_base, addr, next, is_vmemmap, altmap); + free_pte_table(pte_base, pmdp); + } +} + +static void __meminit remove_pud_mapping(pud_t *pud_base, unsigned long ad= dr, unsigned long end, + bool is_vmemmap, struct vmem_altmap *altmap) +{ + unsigned long next; + pud_t *pudp, pud; + pmd_t *pmd_base; + + for (; addr < end; addr =3D next) { + next =3D pud_addr_end(addr, end); + pudp =3D pud_base + pud_index(addr); + pud =3D READ_ONCE(*pudp); + + if (!pud_present(pud)) + continue; + + if (pud_leaf(pud)) { + if (pgtable_l4_enabled) { + pud_clear(pudp); + if (is_vmemmap) + free_vmemmap_storage(pud_page(pud), PUD_SIZE, altmap); + } + continue; + } + + pmd_base =3D pmd_offset(pudp, 0); + remove_pmd_mapping(pmd_base, addr, next, is_vmemmap, altmap); + + if (pgtable_l4_enabled) + free_pmd_table(pmd_base, pudp); + } +} + +static void __meminit remove_p4d_mapping(p4d_t *p4d_base, unsigned long ad= dr, unsigned long end, + bool is_vmemmap, struct vmem_altmap *altmap) +{ + unsigned long next; + p4d_t *p4dp, p4d; + pud_t *pud_base; + + for (; addr < end; addr =3D next) { + next =3D p4d_addr_end(addr, end); + p4dp =3D p4d_base + p4d_index(addr); + p4d =3D READ_ONCE(*p4dp); + + if (!p4d_present(p4d)) + continue; + + if (p4d_leaf(p4d)) { + if (pgtable_l5_enabled) { + p4d_clear(p4dp); + if (is_vmemmap) + free_vmemmap_storage(p4d_page(p4d), P4D_SIZE, altmap); + } + continue; + } + + pud_base =3D pud_offset(p4dp, 0); + remove_pud_mapping(pud_base, addr, next, is_vmemmap, altmap); + + if (pgtable_l5_enabled) + free_pud_table(pud_base, p4dp); + } +} + +static void __meminit remove_pgd_mapping(unsigned long va, unsigned long e= nd, bool is_vmemmap, + struct vmem_altmap *altmap) +{ + unsigned long addr, next; + p4d_t *p4d_base; + pgd_t *pgd; + + for (addr =3D va; addr < end; addr =3D next) { + next =3D pgd_addr_end(addr, end); + pgd =3D pgd_offset_k(addr); + + if (!pgd_present(*pgd)) + continue; + + if (pgd_leaf(*pgd)) + continue; + + p4d_base =3D p4d_offset(pgd, 0); + remove_p4d_mapping(p4d_base, addr, next, is_vmemmap, altmap); + } + + flush_tlb_all(); +} + +static void __meminit remove_linear_mapping(phys_addr_t start, u64 size) +{ + unsigned long va =3D (unsigned long)__va(start); + unsigned long end =3D (unsigned long)__va(start + size); + + remove_pgd_mapping(va, end, false, NULL); +} + +struct range arch_get_mappable_range(void) +{ + struct range mhp_range; + + mhp_range.start =3D __pa(PAGE_OFFSET); + mhp_range.end =3D __pa(PAGE_END - 1); + return mhp_range; +} + +int __ref arch_add_memory(int nid, u64 start, u64 size, struct mhp_params = *params) +{ + int ret =3D 0; + + create_linear_mapping_range(start, start + size, 0, ¶ms->pgprot); + ret =3D __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT, params); + if (ret) { + remove_linear_mapping(start, size); + goto out; + } + + max_pfn =3D PFN_UP(start + size); + max_low_pfn =3D max_pfn; + + out: + flush_tlb_all(); + return ret; +} + +void __ref arch_remove_memory(u64 start, u64 size, struct vmem_altmap *alt= map) +{ + __remove_pages(start >> PAGE_SHIFT, size >> PAGE_SHIFT, altmap); + remove_linear_mapping(start, size); + flush_tlb_all(); +} + +void __ref vmemmap_free(unsigned long start, unsigned long end, struct vme= m_altmap *altmap) +{ + remove_pgd_mapping(start, end, true, altmap); +} +#endif /* CONFIG_MEMORY_HOTPLUG */ --=20 2.40.1