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Message-ID: <20230718234512.1690985-14-seanjc@google.com>
Date:   Tue, 18 Jul 2023 16:44:56 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, Marc Zyngier <maz@...nel.org>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Huacai Chen <chenhuacai@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Anup Patel <anup@...infault.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Sean Christopherson <seanjc@...gle.com>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Paul Moore <paul@...l-moore.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>
Cc:     kvm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.linux.dev, linux-mips@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, kvm-riscv@...ts.infradead.org,
        linux-riscv@...ts.infradead.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Chao Peng <chao.p.peng@...ux.intel.com>,
        Fuad Tabba <tabba@...gle.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Yu Zhang <yu.c.zhang@...ux.intel.com>,
        Vishal Annapurve <vannapurve@...gle.com>,
        Ackerley Tng <ackerleytng@...gle.com>,
        Maciej Szmigiero <mail@...iej.szmigiero.name>,
        Vlastimil Babka <vbabka@...e.cz>,
        David Hildenbrand <david@...hat.com>,
        Quentin Perret <qperret@...gle.com>,
        Michael Roth <michael.roth@....com>,
        Wang <wei.w.wang@...el.com>,
        Liam Merwick <liam.merwick@...cle.com>,
        Isaku Yamahata <isaku.yamahata@...il.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [RFC PATCH v11 13/29] KVM: Add transparent hugepage support for
 dedicated guest memory

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 include/uapi/linux/kvm.h |  2 ++
 virt/kvm/guest_mem.c     | 52 ++++++++++++++++++++++++++++++++++++----
 2 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 9b344fc98598..17b12ee8b70e 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -2290,6 +2290,8 @@ struct kvm_memory_attributes {
 
 #define KVM_CREATE_GUEST_MEMFD	_IOWR(KVMIO,  0xd4, struct kvm_create_guest_memfd)
 
+#define KVM_GUEST_MEMFD_ALLOW_HUGEPAGE		(1ULL << 0)
+
 struct kvm_create_guest_memfd {
 	__u64 size;
 	__u64 flags;
diff --git a/virt/kvm/guest_mem.c b/virt/kvm/guest_mem.c
index 1b705fd63fa8..384671a55b41 100644
--- a/virt/kvm/guest_mem.c
+++ b/virt/kvm/guest_mem.c
@@ -17,15 +17,48 @@ struct kvm_gmem {
 	struct list_head entry;
 };
 
-static struct folio *kvm_gmem_get_folio(struct file *file, pgoff_t index)
+static struct folio *kvm_gmem_get_huge_folio(struct inode *inode, pgoff_t index)
 {
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	unsigned long huge_index = round_down(index, HPAGE_PMD_NR);
+	unsigned long flags = (unsigned long)inode->i_private;
+	struct address_space *mapping  = inode->i_mapping;
+	gfp_t gfp = mapping_gfp_mask(mapping);
 	struct folio *folio;
 
-	/* TODO: Support huge pages. */
-	folio = filemap_grab_folio(file->f_mapping, index);
+	if (!(flags & KVM_GUEST_MEMFD_ALLOW_HUGEPAGE))
+		return NULL;
+
+	if (filemap_range_has_page(mapping, huge_index << PAGE_SHIFT,
+				   (huge_index + HPAGE_PMD_NR - 1) << PAGE_SHIFT))
+		return NULL;
+
+	folio = filemap_alloc_folio(gfp, HPAGE_PMD_ORDER);
 	if (!folio)
 		return NULL;
 
+	if (filemap_add_folio(mapping, folio, huge_index, gfp)) {
+		folio_put(folio);
+		return NULL;
+	}
+
+	return folio;
+#else
+	return NULL;
+#endif
+}
+
+static struct folio *kvm_gmem_get_folio(struct inode *inode, pgoff_t index)
+{
+	struct folio *folio;
+
+	folio = kvm_gmem_get_huge_folio(inode, index);
+	if (!folio) {
+		folio = filemap_grab_folio(inode->i_mapping, index);
+		if (!folio)
+			return NULL;
+	}
+
 	/*
 	 * Use the up-to-date flag to track whether or not the memory has been
 	 * zeroed before being handed off to the guest.  There is no backing
@@ -332,7 +365,8 @@ static const struct inode_operations kvm_gmem_iops = {
 	.setattr	= kvm_gmem_setattr,
 };
 
-static int __kvm_gmem_create(struct kvm *kvm, loff_t size, struct vfsmount *mnt)
+static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags,
+			     struct vfsmount *mnt)
 {
 	const char *anon_name = "[kvm-gmem]";
 	const struct qstr qname = QSTR_INIT(anon_name, strlen(anon_name));
@@ -355,6 +389,7 @@ static int __kvm_gmem_create(struct kvm *kvm, loff_t size, struct vfsmount *mnt)
 	inode->i_mode |= S_IFREG;
 	inode->i_size = size;
 	mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
+	mapping_set_large_folios(inode->i_mapping);
 	mapping_set_unevictable(inode->i_mapping);
 	mapping_set_unmovable(inode->i_mapping);
 
@@ -404,6 +439,12 @@ static bool kvm_gmem_is_valid_size(loff_t size, u64 flags)
 	if (size < 0 || !PAGE_ALIGNED(size))
 		return false;
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	if ((flags & KVM_GUEST_MEMFD_ALLOW_HUGEPAGE) &&
+	    !IS_ALIGNED(size, HPAGE_PMD_SIZE))
+		return false;
+#endif
+
 	return true;
 }
 
@@ -413,6 +454,9 @@ int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args)
 	u64 flags = args->flags;
 	u64 valid_flags = 0;
 
+	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
+		valid_flags |= KVM_GUEST_MEMFD_ALLOW_HUGEPAGE;
+
 	if (flags & ~valid_flags)
 		return -EINVAL;
 
-- 
2.41.0.255.g8b1d071c50-goog

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