linux-toradex.git/drivers/xen/privcmd.c, branch v4.20

xen: add new hypercall buffer mapping device

2018-06-22T06:26:42+00:00

For passing arbitrary data from user land to the Xen hypervisor the
Xen tools today are using mlock()ed buffers. Unfortunately the kernel
might change access rights of such buffers for brief periods of time
e.g. for page migration or compaction, leading to access faults in the
hypervisor, as the hypervisor can't use the locks of the kernel.

In order to solve this problem add a new device node to the Xen privcmd
driver to easily allocate hypercall buffers via mmap(). The memory is
allocated in the kernel and just mapped into user space. Marked as
VM_IO the user mapping will not be subject to page migration et al.

Signed-off-by: Juergen Gross 
Reviewed-by: Boris Ostrovsky 
Signed-off-by: Juergen Gross

xen/privcmd: add IOCTL_PRIVCMD_MMAP_RESOURCE

2018-05-14T13:25:37+00:00

My recent Xen patch series introduces a new HYPERVISOR_memory_op to
support direct priv-mapping of certain guest resources (such as ioreq
pages, used by emulators) by a tools domain, rather than having to access
such resources via the guest P2M.

This patch adds the necessary infrastructure to the privcmd driver and
Xen MMU code to support direct resource mapping.

NOTE: The adjustment in the MMU code is partially cosmetic. Xen will now
      allow a PV tools domain to map guest pages either by GFN or MFN, thus
      the term 'mfn' has been swapped for 'pfn' in the lower layers of the
      remap code.

Signed-off-by: Paul Durrant 
Reviewed-by: Boris Ostrovsky 
Signed-off-by: Juergen Gross

xen: Change return type to vm_fault_t

2018-05-14T12:41:34+00:00

Use new return type vm_fault_t for fault handler
in struct vm_operations_struct.

Signed-off-by: Souptick Joarder 
Reviewed-by: Matthew Wilcox 
Reviewed-by: Juergen Gross 
Signed-off-by: Juergen Gross

xen/privcmd: remove unused variable pageidx

2017-11-08T14:15:28+00:00

Variable pageidx is assigned a value but it is never read, hence it
is redundant and can be removed. Cleans up clang warning:

drivers/xen/privcmd.c:199:2: warning: Value stored to 'pageidx'
is never read

Signed-off-by: Colin Ian King 
Reviewed-by: Juergen Gross 
Signed-off-by: Boris Ostrovsky

xen/privcmd: Support correctly 64KB page granularity when mapping memory

2017-06-07T09:23:14+00:00

Commit 5995a68 "xen/privcmd: Add support for Linux 64KB page granularity" did
not go far enough to support 64KB in mmap_batch_fn.

The variable 'nr' is the number of 4KB chunk to map. However, when Linux
is using 64KB page granularity the array of pages (vma->vm_private_data)
contain one page per 64KB. Fix it by incrementing st->index correctly.

Furthermore, st->va is not correctly incremented as PAGE_SIZE !=
XEN_PAGE_SIZE.

Fixes: 5995a68 ("xen/privcmd: Add support for Linux 64KB page granularity")
CC: stable@vger.kernel.org
Reported-by: Feng Kan 
Signed-off-by: Julien Grall 
Reviewed-by: Boris Ostrovsky 
Signed-off-by: Juergen Gross

mm, fs: reduce fault, page_mkwrite, and pfn_mkwrite to take only vmf

2017-02-25T01:46:54+00:00

->fault(), ->page_mkwrite(), and ->pfn_mkwrite() calls do not need to
take a vma and vmf parameter when the vma already resides in vmf.

Remove the vma parameter to simplify things.

[arnd@arndb.de: fix ARM build]
  Link: http://lkml.kernel.org/r/20170125223558.1451224-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/148521301778.19116.10840599906674778980.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang 
Signed-off-by: Arnd Bergmann 
Reviewed-by: Ross Zwisler 
Cc: Theodore Ts'o 
Cc: Darrick J. Wong 
Cc: Matthew Wilcox 
Cc: Dave Hansen 
Cc: Christoph Hellwig 
Cc: Jan Kara 
Cc: Dan Williams 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

xen/privcmd: add IOCTL_PRIVCMD_RESTRICT

2017-02-14T20:14:59+00:00

The purpose if this ioctl is to allow a user of privcmd to restrict its
operation such that it will no longer service arbitrary hypercalls via
IOCTL_PRIVCMD_HYPERCALL, and will check for a matching domid when
servicing IOCTL_PRIVCMD_DM_OP or IOCTL_PRIVCMD_MMAP*. The aim of this
is to limit the attack surface for a compromised device model.

Signed-off-by: Paul Durrant 
Signed-off-by: Boris Ostrovsky

xen/privcmd: Add IOCTL_PRIVCMD_DM_OP

2017-02-14T20:13:43+00:00

Recently a new dm_op[1] hypercall was added to Xen to provide a mechanism
for restricting device emulators (such as QEMU) to a limited set of
hypervisor operations, and being able to audit those operations in the
kernel of the domain in which they run.

This patch adds IOCTL_PRIVCMD_DM_OP as gateway for __HYPERVISOR_dm_op.

NOTE: There is no requirement for user-space code to bounce data through
      locked memory buffers (as with IOCTL_PRIVCMD_HYPERCALL) since
      privcmd has enough information to lock the original buffers
      directly.

[1] http://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=524a98c2

Signed-off-by: Paul Durrant 
Acked-by: Stefano Stabellini 
Signed-off-by: Boris Ostrovsky

xen/privcmd: return -ENOTTY for unimplemented IOCTLs

2017-02-13T18:49:00+00:00

The code sets the default return code to -ENOSYS but then overrides this
to -EINVAL in the switch() statement's default case, which is clearly
silly.

This patch removes the override and sets the default return code to
-ENOTTY, which is the conventional return for an unimplemented ioctl.

Signed-off-by: Paul Durrant 
Signed-off-by: Boris Ostrovsky

mm: use vmf->address instead of of vmf->virtual_address

2016-12-15T00:04:09+00:00

Every single user of vmf->virtual_address typed that entry to unsigned
long before doing anything with it so the type of virtual_address does
not really provide us any additional safety.  Just use masked
vmf->address which already has the appropriate type.

Link: http://lkml.kernel.org/r/1479460644-25076-3-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara 
Acked-by: Kirill A. Shutemov 
Cc: Dan Williams 
Cc: Ross Zwisler 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds