KVM Archive on lore.kernel.org
 help / color / Atom feed
From: Joao Martins <joao.m.martins@oracle.com>
To: linux-nvdimm@lists.01.org
Cc: Dan Williams <dan.j.williams@intel.com>,
	Vishal Verma <vishal.l.verma@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Ira Weiny <ira.weiny@intel.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	kvm@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H . Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Liran Alon <liran.alon@oracle.com>,
	Nikita Leshenko <nikita.leshchenko@oracle.com>,
	Barret Rhoden <brho@google.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Matthew Wilcox <willy@infradead.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: [PATCH RFC 02/10] mm: Handle pmd entries in follow_pfn()
Date: Fri, 10 Jan 2020 19:03:05 +0000
Message-ID: <20200110190313.17144-3-joao.m.martins@oracle.com> (raw)
In-Reply-To: <20200110190313.17144-1-joao.m.martins@oracle.com>

When follow_pfn hits a pmd_huge() it won't return a valid PFN
given it's usage of follow_pte(). Fix that up to pass a @pmdpp
and thus allow callers to get the pmd pointer. If we encounter
such a huge page, we calculate the pfn offset to the PMD
accordingly.

This allows KVM to handle 2M hugepage pfns on VM_PFNMAP vmas.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
 mm/memory.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index cfc3668bddeb..db99684d2cb3 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4366,6 +4366,7 @@ EXPORT_SYMBOL(follow_pte_pmd);
 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
 	unsigned long *pfn)
 {
+	pmd_t *pmdpp = NULL;
 	int ret = -EINVAL;
 	spinlock_t *ptl;
 	pte_t *ptep;
@@ -4373,10 +4374,14 @@ int follow_pfn(struct vm_area_struct *vma, unsigned long address,
 	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
 		return ret;
 
-	ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
+	ret = follow_pte_pmd(vma->vm_mm, address, NULL,
+			     &ptep, &pmdpp, &ptl);
 	if (ret)
 		return ret;
-	*pfn = pte_pfn(*ptep);
+	if (pmdpp)
+		*pfn = pmd_pfn(*pmdpp) + ((address & ~PMD_MASK) >> PAGE_SHIFT);
+	else
+		*pfn = pte_pfn(*ptep);
 	pte_unmap_unlock(ptep, ptl);
 	return 0;
 }
-- 
2.17.1


  parent reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-10 19:03 [PATCH RFC 00/10] device-dax: Support devices without PFN metadata Joao Martins
2020-01-10 19:03 ` [PATCH RFC 01/10] mm: Add pmd support for _PAGE_SPECIAL Joao Martins
2020-02-03 21:34   ` Matthew Wilcox
2020-02-04 16:14     ` Joao Martins
2020-01-10 19:03 ` Joao Martins [this message]
2020-02-03 21:37   ` [PATCH RFC 02/10] mm: Handle pmd entries in follow_pfn() Matthew Wilcox
2020-02-04 16:17     ` Joao Martins
2020-01-10 19:03 ` [PATCH RFC 03/10] mm: Add pud support for _PAGE_SPECIAL Joao Martins
2020-01-10 19:03 ` [PATCH RFC 04/10] mm: Handle pud entries in follow_pfn() Joao Martins
2020-01-10 19:03 ` [PATCH RFC 05/10] device-dax: Do not enforce MADV_DONTFORK on mmap() Joao Martins
2020-01-10 19:03 ` [PATCH RFC 06/10] device-dax: Introduce pfn_flags helper Joao Martins
2020-01-10 19:03 ` [PATCH RFC 07/10] device-dax: Add support for PFN_SPECIAL flags Joao Martins
2020-01-10 19:03 ` [PATCH RFC 08/10] dax/pmem: Add device-dax support for PFN_MODE_NONE Joao Martins
2020-01-10 19:03 ` [PATCH RFC 09/10] vfio/type1: Use follow_pfn for VM_FPNMAP VMAs Joao Martins
2020-02-07 21:08   ` Jason Gunthorpe
2020-02-11 16:23     ` Joao Martins
2020-02-11 16:50       ` Jason Gunthorpe
2020-01-10 19:03 ` [PATCH RFC 10/10] nvdimm/e820: add multiple namespaces support Joao Martins
2020-02-04 15:28   ` Barret Rhoden
2020-02-04 16:44     ` Dan Williams
2020-02-04 18:20       ` Barret Rhoden
2020-02-04 19:24         ` Joao Martins
2020-02-04 21:43         ` Dan Williams
2020-02-04 21:57           ` Barret Rhoden
2020-02-04  1:24 ` [PATCH RFC 00/10] device-dax: Support devices without PFN metadata Dan Williams
2020-02-04 19:07   ` Joao Martins

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200110190313.17144-3-joao.m.martins@oracle.com \
    --to=joao.m.martins@oracle.com \
    --cc=akpm@linux-foundation.org \
    --cc=alex.williamson@redhat.com \
    --cc=boris.ostrovsky@oracle.com \
    --cc=bp@alien8.de \
    --cc=brho@google.com \
    --cc=cohuck@redhat.com \
    --cc=dan.j.williams@intel.com \
    --cc=dave.jiang@intel.com \
    --cc=hpa@zytor.com \
    --cc=ira.weiny@intel.com \
    --cc=konrad.wilk@oracle.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-nvdimm@lists.01.org \
    --cc=liran.alon@oracle.com \
    --cc=mingo@redhat.com \
    --cc=nikita.leshchenko@oracle.com \
    --cc=tglx@linutronix.de \
    --cc=vishal.l.verma@intel.com \
    --cc=willy@infradead.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

KVM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kvm/0 kvm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kvm kvm/ https://lore.kernel.org/kvm \
		kvm@vger.kernel.org
	public-inbox-index kvm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.kvm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git