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AJvYcCUkpazH6bM8Ru5q/Os7NpYg71SnMsjcpAF8gyZNSehRMC1zH6voh9Ppqs0TklDLFuJeElZIVLImnHwXzwAW@vger.kernel.org X-Gm-Message-State: AOJu0YyYlVOvDUXUf3RFwSzCMbxDWHsCkmRH0RXZej6/zQq7PdJILqop d7bPj5NJ/52ddajaHsrepMdbGHnQ4Dtus6yetBwH1H16iGq7qtm3vrIeJbfjFien8DdzYQ1Lbf+ HAnk2kxty3iCRsIIPA8bRJw== X-Google-Smtp-Source: AGHT+IGl3WmzH+yO2/mQx4qb1kBF9dOrq8V3rB8nhLLZwxphKAU+/jLPzMK1piBiMErLawYA7pQKxljtm90DB1S9Bg== X-Received: from pjbtb15.prod.google.com ([2002:a17:90b:53cf:b0:2ff:4be0:c675]) (user=ackerleytng job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:1811:b0:30e:3737:7c87 with SMTP id 98e67ed59e1d1-30e4db11d0amr1980560a91.5.1747266222377; Wed, 14 May 2025 16:43:42 -0700 (PDT) Date: Wed, 14 May 2025 16:42:08 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.49.0.1045.g170613ef41-goog Message-ID: Subject: [RFC PATCH v2 29/51] mm: guestmem_hugetlb: Wrap HugeTLB as an allocator for guest_memfd From: Ackerley Tng To: kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-fsdevel@vger.kernel.org Cc: ackerleytng@google.com, aik@amd.com, ajones@ventanamicro.com, akpm@linux-foundation.org, amoorthy@google.com, anthony.yznaga@oracle.com, anup@brainfault.org, aou@eecs.berkeley.edu, bfoster@redhat.com, binbin.wu@linux.intel.com, brauner@kernel.org, catalin.marinas@arm.com, chao.p.peng@intel.com, chenhuacai@kernel.org, dave.hansen@intel.com, david@redhat.com, dmatlack@google.com, dwmw@amazon.co.uk, erdemaktas@google.com, fan.du@intel.com, fvdl@google.com, graf@amazon.com, haibo1.xu@intel.com, hch@infradead.org, hughd@google.com, ira.weiny@intel.com, isaku.yamahata@intel.com, jack@suse.cz, james.morse@arm.com, jarkko@kernel.org, jgg@ziepe.ca, jgowans@amazon.com, jhubbard@nvidia.com, jroedel@suse.de, jthoughton@google.com, jun.miao@intel.com, kai.huang@intel.com, keirf@google.com, kent.overstreet@linux.dev, kirill.shutemov@intel.com, liam.merwick@oracle.com, maciej.wieczor-retman@intel.com, mail@maciej.szmigiero.name, maz@kernel.org, mic@digikod.net, michael.roth@amd.com, mpe@ellerman.id.au, muchun.song@linux.dev, nikunj@amd.com, nsaenz@amazon.es, oliver.upton@linux.dev, palmer@dabbelt.com, pankaj.gupta@amd.com, paul.walmsley@sifive.com, pbonzini@redhat.com, pdurrant@amazon.co.uk, peterx@redhat.com, pgonda@google.com, pvorel@suse.cz, qperret@google.com, quic_cvanscha@quicinc.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, quic_svaddagi@quicinc.com, quic_tsoni@quicinc.com, richard.weiyang@gmail.com, rick.p.edgecombe@intel.com, rientjes@google.com, roypat@amazon.co.uk, rppt@kernel.org, seanjc@google.com, shuah@kernel.org, steven.price@arm.com, steven.sistare@oracle.com, suzuki.poulose@arm.com, tabba@google.com, thomas.lendacky@amd.com, usama.arif@bytedance.com, vannapurve@google.com, vbabka@suse.cz, viro@zeniv.linux.org.uk, vkuznets@redhat.com, wei.w.wang@intel.com, will@kernel.org, willy@infradead.org, xiaoyao.li@intel.com, yan.y.zhao@intel.com, yilun.xu@intel.com, yuzenghui@huawei.com, zhiquan1.li@intel.com Content-Type: text/plain; charset="UTF-8" guestmem_hugetlb is an allocator for guest_memfd. It wraps HugeTLB to provide huge folios for guest_memfd. This patch also introduces guestmem_allocator_operations as a set of operations that allocators for guest_memfd can provide. In a later patch, guest_memfd will use these operations to manage pages from an allocator. The allocator operations are memory-management specific and are placed in mm/ so key mm-specific functions do not have to be exposed unnecessarily. Signed-off-by: Ackerley Tng Change-Id: I3cafe111ea7b3c84755d7112ff8f8c541c11136d --- include/linux/guestmem.h | 20 +++++ include/uapi/linux/guestmem.h | 29 +++++++ mm/Kconfig | 5 +- mm/guestmem_hugetlb.c | 159 ++++++++++++++++++++++++++++++++++ 4 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 include/linux/guestmem.h create mode 100644 include/uapi/linux/guestmem.h diff --git a/include/linux/guestmem.h b/include/linux/guestmem.h new file mode 100644 index 000000000000..4b2d820274d9 --- /dev/null +++ b/include/linux/guestmem.h @@ -0,0 +1,20 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_GUESTMEM_H +#define _LINUX_GUESTMEM_H + +#include + +struct guestmem_allocator_operations { + void *(*inode_setup)(size_t size, u64 flags); + void (*inode_teardown)(void *private, size_t inode_size); + struct folio *(*alloc_folio)(void *private); + /* + * Returns the number of PAGE_SIZE pages in a page that this guestmem + * allocator provides. + */ + size_t (*nr_pages_in_folio)(void *priv); +}; + +extern const struct guestmem_allocator_operations guestmem_hugetlb_ops; + +#endif diff --git a/include/uapi/linux/guestmem.h b/include/uapi/linux/guestmem.h new file mode 100644 index 000000000000..2e518682edd5 --- /dev/null +++ b/include/uapi/linux/guestmem.h @@ -0,0 +1,29 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef _UAPI_LINUX_GUESTMEM_H +#define _UAPI_LINUX_GUESTMEM_H + +/* + * Huge page size must be explicitly defined when using the guestmem_hugetlb + * allocator for guest_memfd. It is the responsibility of the application to + * know which sizes are supported on the running system. See mmap(2) man page + * for details. + */ + +#define GUESTMEM_HUGETLB_FLAG_SHIFT 58 +#define GUESTMEM_HUGETLB_FLAG_MASK 0x3fUL + +#define GUESTMEM_HUGETLB_FLAG_16KB (14UL << GUESTMEM_HUGETLB_FLAG_SHIFT) +#define GUESTMEM_HUGETLB_FLAG_64KB (16UL << GUESTMEM_HUGETLB_FLAG_SHIFT) +#define GUESTMEM_HUGETLB_FLAG_512KB (19UL << GUESTMEM_HUGETLB_FLAG_SHIFT) +#define GUESTMEM_HUGETLB_FLAG_1MB (20UL << GUESTMEM_HUGETLB_FLAG_SHIFT) +#define GUESTMEM_HUGETLB_FLAG_2MB (21UL << GUESTMEM_HUGETLB_FLAG_SHIFT) +#define GUESTMEM_HUGETLB_FLAG_8MB (23UL << GUESTMEM_HUGETLB_FLAG_SHIFT) +#define GUESTMEM_HUGETLB_FLAG_16MB (24UL << GUESTMEM_HUGETLB_FLAG_SHIFT) +#define GUESTMEM_HUGETLB_FLAG_32MB (25UL << GUESTMEM_HUGETLB_FLAG_SHIFT) +#define GUESTMEM_HUGETLB_FLAG_256MB (28UL << GUESTMEM_HUGETLB_FLAG_SHIFT) +#define GUESTMEM_HUGETLB_FLAG_512MB (29UL << GUESTMEM_HUGETLB_FLAG_SHIFT) +#define GUESTMEM_HUGETLB_FLAG_1GB (30UL << GUESTMEM_HUGETLB_FLAG_SHIFT) +#define GUESTMEM_HUGETLB_FLAG_2GB (31UL << GUESTMEM_HUGETLB_FLAG_SHIFT) +#define GUESTMEM_HUGETLB_FLAG_16GB (34UL << GUESTMEM_HUGETLB_FLAG_SHIFT) + +#endif /* _UAPI_LINUX_GUESTMEM_H */ diff --git a/mm/Kconfig b/mm/Kconfig index 131adc49f58d..bb6e39e37245 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -1218,7 +1218,10 @@ config SECRETMEM config GUESTMEM_HUGETLB bool "Enable guestmem_hugetlb allocator for guest_memfd" - depends on HUGETLBFS + select GUESTMEM + select HUGETLBFS + select HUGETLB_PAGE + select HUGETLB_PAGE_OPTIMIZE_VMEMMAP help Enable this to make HugeTLB folios available to guest_memfd (KVM virtualization) as backing memory. diff --git a/mm/guestmem_hugetlb.c b/mm/guestmem_hugetlb.c index 51a724ebcc50..5459ef7eb329 100644 --- a/mm/guestmem_hugetlb.c +++ b/mm/guestmem_hugetlb.c @@ -5,6 +5,14 @@ */ #include +#include +#include +#include +#include +#include +#include + +#include #include "guestmem_hugetlb.h" @@ -12,3 +20,154 @@ void guestmem_hugetlb_handle_folio_put(struct folio *folio) { WARN_ONCE(1, "A placeholder that shouldn't trigger. Work in progress."); } + +struct guestmem_hugetlb_private { + struct hstate *h; + struct hugepage_subpool *spool; + struct hugetlb_cgroup *h_cg_rsvd; +}; + +static size_t guestmem_hugetlb_nr_pages_in_folio(void *priv) +{ + struct guestmem_hugetlb_private *private = priv; + + return pages_per_huge_page(private->h); +} + +static void *guestmem_hugetlb_setup(size_t size, u64 flags) + +{ + struct guestmem_hugetlb_private *private; + struct hugetlb_cgroup *h_cg_rsvd = NULL; + struct hugepage_subpool *spool; + unsigned long nr_pages; + int page_size_log; + struct hstate *h; + long hpages; + int idx; + int ret; + + page_size_log = (flags >> GUESTMEM_HUGETLB_FLAG_SHIFT) & + GUESTMEM_HUGETLB_FLAG_MASK; + h = hstate_sizelog(page_size_log); + if (!h) + return ERR_PTR(-EINVAL); + + /* + * Check against h because page_size_log could be 0 to request default + * HugeTLB page size. + */ + if (!IS_ALIGNED(size, huge_page_size(h))) + return ERR_PTR(-EINVAL); + + private = kzalloc(sizeof(*private), GFP_KERNEL); + if (!private) + return ERR_PTR(-ENOMEM); + + /* Creating a subpool makes reservations, hence charge for them now. */ + idx = hstate_index(h); + nr_pages = size >> PAGE_SHIFT; + ret = hugetlb_cgroup_charge_cgroup_rsvd(idx, nr_pages, &h_cg_rsvd); + if (ret) + goto err_free; + + hpages = size >> huge_page_shift(h); + spool = hugepage_new_subpool(h, hpages, hpages, false); + if (!spool) + goto err_uncharge; + + private->h = h; + private->spool = spool; + private->h_cg_rsvd = h_cg_rsvd; + + return private; + +err_uncharge: + ret = -ENOMEM; + hugetlb_cgroup_uncharge_cgroup_rsvd(idx, nr_pages, h_cg_rsvd); +err_free: + kfree(private); + return ERR_PTR(ret); +} + +static void guestmem_hugetlb_teardown(void *priv, size_t inode_size) +{ + struct guestmem_hugetlb_private *private = priv; + unsigned long nr_pages; + int idx; + + hugepage_put_subpool(private->spool); + + idx = hstate_index(private->h); + nr_pages = inode_size >> PAGE_SHIFT; + hugetlb_cgroup_uncharge_cgroup_rsvd(idx, nr_pages, private->h_cg_rsvd); + + kfree(private); +} + +static struct folio *guestmem_hugetlb_alloc_folio(void *priv) +{ + struct guestmem_hugetlb_private *private = priv; + struct mempolicy *mpol; + struct folio *folio; + pgoff_t ilx; + int ret; + + ret = hugepage_subpool_get_pages(private->spool, 1); + if (ret == -ENOMEM) { + return ERR_PTR(-ENOMEM); + } else if (ret > 0) { + /* guest_memfd will not use surplus pages. */ + goto err_put_pages; + } + + /* + * TODO: mempolicy would probably have to be stored on the inode, use + * task policy for now. + */ + mpol = get_task_policy(current); + + /* TODO: ignore interleaving for now. */ + ilx = NO_INTERLEAVE_INDEX; + + /* + * charge_cgroup_rsvd is false because we already charged reservations + * when creating the subpool for this + * guest_memfd. use_existing_reservation is true - we're using a + * reservation from the guest_memfd's subpool. + */ + folio = hugetlb_alloc_folio(private->h, mpol, ilx, false, true); + mpol_cond_put(mpol); + + if (IS_ERR_OR_NULL(folio)) + goto err_put_pages; + + /* + * Clear restore_reserve here so that when this folio is freed, + * free_huge_folio() will always attempt to return the reservation to + * the subpool. guest_memfd, unlike regular hugetlb, has no resv_map, + * and hence when freeing, the folio needs to be returned to the + * subpool. guest_memfd does not use surplus hugetlb pages, so in + * free_huge_folio(), returning to subpool will always succeed and the + * hstate reservation will then get restored. + * + * hugetlbfs does this in hugetlb_add_to_page_cache(). + */ + folio_clear_hugetlb_restore_reserve(folio); + + hugetlb_set_folio_subpool(folio, private->spool); + + return folio; + +err_put_pages: + hugepage_subpool_put_pages(private->spool, 1); + return ERR_PTR(-ENOMEM); +} + +const struct guestmem_allocator_operations guestmem_hugetlb_ops = { + .inode_setup = guestmem_hugetlb_setup, + .inode_teardown = guestmem_hugetlb_teardown, + .alloc_folio = guestmem_hugetlb_alloc_folio, + .nr_pages_in_folio = guestmem_hugetlb_nr_pages_in_folio, +}; +EXPORT_SYMBOL_GPL(guestmem_hugetlb_ops); -- 2.49.0.1045.g170613ef41-goog