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Message-ID: <727b9efc-f448-2955-6a47-774de330bcd8@oracle.com>
Date: Thu, 5 Apr 2018 18:33:30 -0400
From: Boris Ostrovsky <boris.ostrovsky@...cle.com>
To: Paul Durrant <paul.durrant@...rix.com>, x86@...nel.org,
xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Cc: Juergen Gross <jgross@...e.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH v2] xen/privcmd: add IOCTL_PRIVCMD_MMAP_RESOURCE
On 04/05/2018 11:42 AM, Paul Durrant wrote:
> 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 <paul.durrant@...rix.com>
> ---
> Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> Cc: Juergen Gross <jgross@...e.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
>
> v2:
> - Fix bug when mapping multiple pages of a resource
Only a few nits below.
> ---
> arch/x86/xen/mmu.c | 50 +++++++++++-----
> drivers/xen/privcmd.c | 130 +++++++++++++++++++++++++++++++++++++++++
> include/uapi/xen/privcmd.h | 11 ++++
> include/xen/interface/memory.h | 66 +++++++++++++++++++++
> include/xen/interface/xen.h | 7 ++-
> include/xen/xen-ops.h | 24 +++++++-
> 6 files changed, 270 insertions(+), 18 deletions(-)
>
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index d33e7dbe3129..8453d7be415c 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -65,37 +65,42 @@ static void xen_flush_tlb_all(void)
> #define REMAP_BATCH_SIZE 16
>
> struct remap_data {
> - xen_pfn_t *mfn;
> + xen_pfn_t *pfn;
> bool contiguous;
> + bool no_translate;
> pgprot_t prot;
> struct mmu_update *mmu_update;
> };
>
> -static int remap_area_mfn_pte_fn(pte_t *ptep, pgtable_t token,
> +static int remap_area_pfn_pte_fn(pte_t *ptep, pgtable_t token,
> unsigned long addr, void *data)
> {
> struct remap_data *rmd = data;
> - pte_t pte = pte_mkspecial(mfn_pte(*rmd->mfn, rmd->prot));
> + pte_t pte = pte_mkspecial(mfn_pte(*rmd->pfn, rmd->prot));
>
> /* If we have a contiguous range, just update the mfn itself,
> else update pointer to be "next mfn". */
This probably also needs to be updated (and while at it, comment style
fixed)
> if (rmd->contiguous)
> - (*rmd->mfn)++;
> + (*rmd->pfn)++;
> else
> - rmd->mfn++;
> + rmd->pfn++;
>
> - rmd->mmu_update->ptr = virt_to_machine(ptep).maddr | MMU_NORMAL_PT_UPDATE;
> + rmd->mmu_update->ptr = virt_to_machine(ptep).maddr;
> + rmd->mmu_update->ptr |= rmd->no_translate ?
> + MMU_PT_UPDATE_NO_TRANSLATE :
> + MMU_NORMAL_PT_UPDATE;
> rmd->mmu_update->val = pte_val_ma(pte);
> rmd->mmu_update++;
>
> return 0;
> }
>
> -static int do_remap_gfn(struct vm_area_struct *vma,
> +static int do_remap_pfn(struct vm_area_struct *vma,
> unsigned long addr,
> - xen_pfn_t *gfn, int nr,
> + xen_pfn_t *pfn, int nr,
> int *err_ptr, pgprot_t prot,
> - unsigned domid,
> + unsigned int domid,
> + bool no_translate,
> struct page **pages)
> {
> int err = 0;
> @@ -106,11 +111,12 @@ static int do_remap_gfn(struct vm_area_struct *vma,
>
> BUG_ON(!((vma->vm_flags & (VM_PFNMAP | VM_IO)) == (VM_PFNMAP | VM_IO)));
>
> - rmd.mfn = gfn;
> + rmd.pfn = pfn;
> rmd.prot = prot;
> /* We use the err_ptr to indicate if there we are doing a contiguous
> * mapping or a discontigious mapping. */
Style.
> rmd.contiguous = !err_ptr;
> + rmd.no_translate = no_translate;
>
> while (nr) {
> int index = 0;
> @@ -121,7 +127,7 @@ static int do_remap_gfn(struct vm_area_struct *vma,
>
> rmd.mmu_update = mmu_update;
> err = apply_to_page_range(vma->vm_mm, addr, range,
> - remap_area_mfn_pte_fn, &rmd);
> + remap_area_pfn_pte_fn, &rmd);
> if (err)
> goto out;
>
> @@ -175,7 +181,8 @@ int xen_remap_domain_gfn_range(struct vm_area_struct *vma,
> if (xen_feature(XENFEAT_auto_translated_physmap))
> return -EOPNOTSUPP;
>
> - return do_remap_gfn(vma, addr, &gfn, nr, NULL, prot, domid, pages);
> + return do_remap_pfn(vma, addr, &gfn, nr, NULL, prot, domid, false,
> + pages);
> }
> EXPORT_SYMBOL_GPL(xen_remap_domain_gfn_range);
>
> @@ -183,7 +190,7 @@ int xen_remap_domain_gfn_array(struct vm_area_struct *vma,
> unsigned long addr,
> xen_pfn_t *gfn, int nr,
> int *err_ptr, pgprot_t prot,
> - unsigned domid, struct page **pages)
> + unsigned int domid, struct page **pages)
Is this really necessary? And if it is, then why are other routines
(e.g. xen_remap_domain_gfn_range() above) not updated as well?
> {
> if (xen_feature(XENFEAT_auto_translated_physmap))
> return xen_xlate_remap_gfn_array(vma, addr, gfn, nr, err_ptr,
> @@ -194,10 +201,25 @@ int xen_remap_domain_gfn_array(struct vm_area_struct *vma,
> * cause of "wrong memory was mapped in".
> */
> BUG_ON(err_ptr == NULL);
> - return do_remap_gfn(vma, addr, gfn, nr, err_ptr, prot, domid, pages);
> + return do_remap_pfn(vma, addr, gfn, nr, err_ptr, prot, domid,
> + false, pages);
> }
> EXPORT_SYMBOL_GPL(xen_remap_domain_gfn_array);
>
> +int xen_remap_domain_mfn_array(struct vm_area_struct *vma,
> + unsigned long addr,
> + xen_pfn_t *mfn, int nr,
> + int *err_ptr, pgprot_t prot,
> + unsigned int domid, struct page **pages)
> +{
> + if (xen_feature(XENFEAT_auto_translated_physmap))
> + return -EOPNOTSUPP;
> +
> + return do_remap_pfn(vma, addr, mfn, nr, err_ptr, prot, domid,
> + true, pages);
> +}
> +EXPORT_SYMBOL_GPL(xen_remap_domain_mfn_array);
> +
> /* Returns: 0 success */
> int xen_unmap_domain_gfn_range(struct vm_area_struct *vma,
> int nr, struct page **pages)
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index 1c909183c42a..cca809a204ab 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -33,6 +33,7 @@
> #include <xen/xen.h>
> #include <xen/privcmd.h>
> #include <xen/interface/xen.h>
> +#include <xen/interface/memory.h>
> #include <xen/interface/hvm/dm_op.h>
> #include <xen/features.h>
> #include <xen/page.h>
> @@ -722,6 +723,131 @@ static long privcmd_ioctl_restrict(struct file *file, void __user *udata)
> return 0;
> }
>
> +struct remap_pfn {
> + struct mm_struct *mm;
> + struct page **pages;
> + pgprot_t prot;
> + unsigned long i;
> +};
> +
> +static int remap_pfn(pte_t *ptep, pgtable_t token, unsigned long addr,
Maybe remap_pfn_fn (to avoid name shadowing)?
> + void *data)
> +{
> + struct remap_pfn *r = data;
> + struct page *page = r->pages[r->i];
> + pte_t pte = pte_mkspecial(pfn_pte(page_to_pfn(page), r->prot));
> +
> + set_pte_at(r->mm, addr, ptep, pte);
> + r->i++;
> +
> + return 0;
> +}
> +
> +static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata)
> +{
> + struct privcmd_data *data = file->private_data;
> + struct mm_struct *mm = current->mm;
> + struct vm_area_struct *vma;
> + struct privcmd_mmap_resource kdata;
> + xen_pfn_t *pfns = NULL;
> + struct xen_mem_acquire_resource xdata;
> + int rc;
> +
> + if (copy_from_user(&kdata, udata, sizeof(kdata)))
> + return -EFAULT;
> +
> + /* If restriction is in place, check the domid matches */
> + if (data->domid != DOMID_INVALID && data->domid != kdata.dom)
> + return -EPERM;
> +
> + down_write(&mm->mmap_sem);
> +
> + vma = find_vma(mm, kdata.addr);
> + if (!vma || vma->vm_ops != &privcmd_vm_ops) {
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + pfns = kcalloc(kdata.num, sizeof(*pfns), GFP_KERNEL);
> + if (!pfns) {
> + rc = -ENOMEM;
> + goto out;
> + }
> +
> + if (xen_feature(XENFEAT_auto_translated_physmap)) {
> + struct page **pages;
> + unsigned int i;
> +
> + rc = alloc_empty_pages(vma, kdata.num);
> + if (rc < 0)
> + goto out;
> +
> + pages = vma->vm_private_data;
> + for (i = 0; i < kdata.num; i++) {
> + pfns[i] = page_to_pfn(pages[i]);
> + pr_info("pfn[%u] = %p\n", i, (void *)pfns[i]);
> + }
> + } else
> + vma->vm_private_data = PRIV_VMA_LOCKED;
> +
> + memset(&xdata, 0, sizeof(xdata));
> + xdata.domid = kdata.dom;
> + xdata.type = kdata.type;
> + xdata.id = kdata.id;
> + xdata.frame = kdata.idx;
> + xdata.nr_frames = kdata.num;
> + set_xen_guest_handle(xdata.frame_list, pfns);
> +
> + xen_preemptible_hcall_begin();
> + rc = HYPERVISOR_memory_op(XENMEM_acquire_resource, &xdata);
> + xen_preemptible_hcall_end();
> +
> + if (rc)
> + goto out;
> +
> + if (xen_feature(XENFEAT_auto_translated_physmap)) {
> + struct remap_pfn r = {
> + .mm = vma->vm_mm,
> + .pages = vma->vm_private_data,
> + .prot = vma->vm_page_prot,
> + };
> +
> + rc = apply_to_page_range(r.mm, kdata.addr,
> + kdata.num << PAGE_SHIFT,
> + remap_pfn, &r);
> + } else {
> + unsigned int domid =
> + (xdata.flags & XENMEM_rsrc_acq_caller_owned) ?
> + DOMID_SELF : kdata.dom;
> + int num;
> +
> + num = xen_remap_domain_mfn_array(vma,
> + kdata.addr & PAGE_MASK,
> + pfns, kdata.num, (int *)pfns,
> + vma->vm_page_prot,
> + domid,
> + vma->vm_private_data);
> + if (num < 0)
> + rc = num;
> + else if (num != kdata.num) {
> + unsigned int i;
> +
> + for (i = 0; i < num; i++) {
> + rc = pfns[i];
> + if (rc < 0)
> + break;
> + }
> + } else
> + rc = 0;
> + }
> +
> +out:
> + kfree(pfns);
> +
> + up_write(&mm->mmap_sem);
I'd swap these two.
-boris
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