forked from Minki/linux
0df4f266b3
Based on include/xen/mm.h [1], Linux is mistakenly using MFN when GFN is meant, I suspect this is because the first support for Xen was for PV. This resulted in some misimplementation of helpers on ARM and confused developers about the expected behavior. For instance, with pfn_to_mfn, we expect to get an MFN based on the name. Although, if we look at the implementation on x86, it's returning a GFN. For clarity and avoid new confusion, replace any reference to mfn with gfn in any helpers used by PV drivers. The x86 code will still keep some reference of pfn_to_mfn which may be used by all kind of guests No changes as been made in the hypercall field, even though they may be invalid, in order to keep the same as the defintion in xen repo. Note that page_to_mfn has been renamed to xen_page_to_gfn to avoid a name to close to the KVM function gfn_to_page. Take also the opportunity to simplify simple construction such as pfn_to_mfn(page_to_pfn(page)) into xen_page_to_gfn. More complex clean up will come in follow-up patches. [1] http://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=e758ed14f390342513405dd766e874934573e6cb Signed-off-by: Julien Grall <julien.grall@citrix.com> Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Acked-by: Wei Liu <wei.liu2@citrix.com> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
143 lines
3.1 KiB
C
143 lines
3.1 KiB
C
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/miscdevice.h>
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#include <linux/module.h>
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#include <linux/capability.h>
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#include <xen/xen.h>
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#include <xen/page.h>
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#include <xen/xenbus.h>
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#include <xen/xenbus_dev.h>
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#include <xen/grant_table.h>
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#include <xen/events.h>
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#include <asm/xen/hypervisor.h>
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#include "xenbus_comms.h"
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MODULE_LICENSE("GPL");
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static int xenbus_backend_open(struct inode *inode, struct file *filp)
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{
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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return nonseekable_open(inode, filp);
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}
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static long xenbus_alloc(domid_t domid)
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{
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struct evtchn_alloc_unbound arg;
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int err = -EEXIST;
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xs_suspend();
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/* If xenstored_ready is nonzero, that means we have already talked to
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* xenstore and set up watches. These watches will be restored by
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* xs_resume, but that requires communication over the port established
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* below that is not visible to anyone until the ioctl returns.
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*
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* This can be resolved by splitting the ioctl into two parts
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* (postponing the resume until xenstored is active) but this is
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* unnecessarily complex for the intended use where xenstored is only
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* started once - so return -EEXIST if it's already running.
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*/
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if (xenstored_ready)
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goto out_err;
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gnttab_grant_foreign_access_ref(GNTTAB_RESERVED_XENSTORE, domid,
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virt_to_gfn(xen_store_interface), 0 /* writable */);
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arg.dom = DOMID_SELF;
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arg.remote_dom = domid;
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err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, &arg);
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if (err)
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goto out_err;
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if (xen_store_evtchn > 0)
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xb_deinit_comms();
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xen_store_evtchn = arg.port;
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xs_resume();
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return arg.port;
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out_err:
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xs_suspend_cancel();
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return err;
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}
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static long xenbus_backend_ioctl(struct file *file, unsigned int cmd,
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unsigned long data)
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{
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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switch (cmd) {
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case IOCTL_XENBUS_BACKEND_EVTCHN:
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if (xen_store_evtchn > 0)
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return xen_store_evtchn;
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return -ENODEV;
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case IOCTL_XENBUS_BACKEND_SETUP:
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return xenbus_alloc(data);
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default:
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return -ENOTTY;
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}
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}
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static int xenbus_backend_mmap(struct file *file, struct vm_area_struct *vma)
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{
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size_t size = vma->vm_end - vma->vm_start;
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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if ((size > PAGE_SIZE) || (vma->vm_pgoff != 0))
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return -EINVAL;
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if (remap_pfn_range(vma, vma->vm_start,
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virt_to_pfn(xen_store_interface),
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size, vma->vm_page_prot))
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return -EAGAIN;
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return 0;
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}
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static const struct file_operations xenbus_backend_fops = {
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.open = xenbus_backend_open,
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.mmap = xenbus_backend_mmap,
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.unlocked_ioctl = xenbus_backend_ioctl,
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};
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static struct miscdevice xenbus_backend_dev = {
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.minor = MISC_DYNAMIC_MINOR,
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.name = "xen/xenbus_backend",
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.fops = &xenbus_backend_fops,
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};
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static int __init xenbus_backend_init(void)
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{
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int err;
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if (!xen_initial_domain())
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return -ENODEV;
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err = misc_register(&xenbus_backend_dev);
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if (err)
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pr_err("Could not register xenbus backend device\n");
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return err;
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}
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static void __exit xenbus_backend_exit(void)
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{
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misc_deregister(&xenbus_backend_dev);
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}
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module_init(xenbus_backend_init);
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module_exit(xenbus_backend_exit);
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