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    Subject[PATCH 6/6] xen/pvh: /dev/xen/privcmd changes.
    Date
    From: Mukesh Rathor <mukesh.rathor@oracle.com>

    PVH only supports the batch interface. To map a foreign page to a process,
    the PFN must be allocated and PVH path uses ballooning for that purpose.

    The returned PFN is then mapped to the foreign page.
    xen_unmap_domain_mfn_range() is introduced to unmap these pages via the
    privcmd close call.

    Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
    [v1: Fix up privcmd_close]
    Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    ---
    drivers/xen/privcmd.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++-
    1 files changed, 67 insertions(+), 2 deletions(-)

    diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
    index b612267..b9d0898 100644
    --- a/drivers/xen/privcmd.c
    +++ b/drivers/xen/privcmd.c
    @@ -33,11 +33,14 @@
    #include <xen/features.h>
    #include <xen/page.h>
    #include <xen/xen-ops.h>
    +#include <xen/balloon.h>

    #include "privcmd.h"

    MODULE_LICENSE("GPL");

    +#define PRIV_VMA_LOCKED ((void *)1)
    +
    #ifndef HAVE_ARCH_PRIVCMD_MMAP
    static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma);
    #endif
    @@ -199,6 +202,10 @@ static long privcmd_ioctl_mmap(void __user *udata)
    if (!xen_initial_domain())
    return -EPERM;

    + /* We only support privcmd_ioctl_mmap_batch for auto translated. */
    + if (xen_feature(XENFEAT_auto_translated_physmap))
    + return -ENOSYS;
    +
    if (copy_from_user(&mmapcmd, udata, sizeof(mmapcmd)))
    return -EFAULT;

    @@ -246,6 +253,7 @@ struct mmap_batch_state {
    domid_t domain;
    unsigned long va;
    struct vm_area_struct *vma;
    + int index;
    /* A tristate:
    * 0 for no errors
    * 1 if at least one error has happened (and no
    @@ -260,15 +268,24 @@ struct mmap_batch_state {
    xen_pfn_t __user *user_mfn;
    };

    +/* auto translated dom0 note: if domU being created is PV, then mfn is
    + * mfn(addr on bus). If it's auto xlated, then mfn is pfn (input to HAP).
    + */
    static int mmap_batch_fn(void *data, void *state)
    {
    xen_pfn_t *mfnp = data;
    struct mmap_batch_state *st = state;
    + struct vm_area_struct *vma = st->vma;
    + struct page **pages = vma->vm_private_data;
    + struct page *cur_page = NULL;
    int ret;

    + if (xen_feature(XENFEAT_auto_translated_physmap))
    + cur_page = pages[st->index++];
    +
    ret = xen_remap_domain_mfn_range(st->vma, st->va & PAGE_MASK, *mfnp, 1,
    st->vma->vm_page_prot, st->domain,
    - NULL);
    + &cur_page);

    /* Store error code for second pass. */
    *(st->err++) = ret;
    @@ -304,6 +321,32 @@ static int mmap_return_errors_v1(void *data, void *state)
    return __put_user(*mfnp, st->user_mfn++);
    }

    +/* Allocate pfns that are then mapped with gmfns from foreign domid. Update
    + * the vma with the page info to use later.
    + * Returns: 0 if success, otherwise -errno
    + */
    +static int alloc_empty_pages(struct vm_area_struct *vma, int numpgs)
    +{
    + int rc;
    + struct page **pages;
    +
    + pages = kcalloc(numpgs, sizeof(pages[0]), GFP_KERNEL);
    + if (pages == NULL)
    + return -ENOMEM;
    +
    + rc = alloc_xenballooned_pages(numpgs, pages, 0);
    + if (rc != 0) {
    + pr_warn("%s Could not alloc %d pfns rc:%d\n", __func__,
    + numpgs, rc);
    + kfree(pages);
    + return -ENOMEM;
    + }
    + BUG_ON(vma->vm_private_data != PRIV_VMA_LOCKED);
    + vma->vm_private_data = pages;
    +
    + return 0;
    +}
    +
    static struct vm_operations_struct privcmd_vm_ops;

    static long privcmd_ioctl_mmap_batch(void __user *udata, int version)
    @@ -371,10 +414,18 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version)
    up_write(&mm->mmap_sem);
    goto out;
    }
    + if (xen_feature(XENFEAT_auto_translated_physmap)) {
    + ret = alloc_empty_pages(vma, m.num);
    + if (ret < 0) {
    + up_write(&mm->mmap_sem);
    + goto out;
    + }
    + }

    state.domain = m.dom;
    state.vma = vma;
    state.va = m.addr;
    + state.index = 0;
    state.global_error = 0;
    state.err = err_array;

    @@ -439,6 +490,19 @@ static long privcmd_ioctl(struct file *file,
    return ret;
    }

    +static void privcmd_close(struct vm_area_struct *vma)
    +{
    + struct page **pages = vma->vm_private_data;
    + int numpgs = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
    +
    + if (!xen_feature(XENFEAT_auto_translated_physmap || !numpgs || !pages))
    + return;
    +
    + xen_unmap_domain_mfn_range(vma, numpgs, pages);
    + free_xenballooned_pages(numpgs, pages);
    + kfree(pages);
    +}
    +
    static int privcmd_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
    {
    printk(KERN_DEBUG "privcmd_fault: vma=%p %lx-%lx, pgoff=%lx, uv=%p\n",
    @@ -449,6 +513,7 @@ static int privcmd_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
    }

    static struct vm_operations_struct privcmd_vm_ops = {
    + .close = privcmd_close,
    .fault = privcmd_fault
    };

    @@ -466,7 +531,7 @@ static int privcmd_mmap(struct file *file, struct vm_area_struct *vma)

    static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma)
    {
    - return (xchg(&vma->vm_private_data, (void *)1) == NULL);
    + return !cmpxchg(&vma->vm_private_data, NULL, PRIV_VMA_LOCKED);
    }

    const struct file_operations xen_privcmd_fops = {
    --
    1.7.7.6


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