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SubjectRE: [PATCH v5] xen/privcmd: add IOCTL_PRIVCMD_MMAP_RESOURCE
Date
Apoligies. I appear to have already sent this a while ago.

Paul

> -----Original Message-----
> From: Paul Durrant [mailto:paul.durrant@citrix.com]
> Sent: 09 May 2018 14:16
> To: xen-devel@lists.xenproject.org; linux-kernel@vger.kernel.org; linux-
> arm-kernel@lists.infradead.org
> Cc: Paul Durrant <Paul.Durrant@citrix.com>; Juergen Gross
> <jgross@suse.com>; Thomas Gleixner <tglx@linutronix.de>; Ingo Molnar
> <mingo@redhat.com>; Stefano Stabellini <sstabellini@kernel.org>
> Subject: [PATCH v5] xen/privcmd: add IOCTL_PRIVCMD_MMAP_RESOURCE
>
> 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@citrix.com>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> ---
> Cc: Juergen Gross <jgross@suse.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Stefano Stabellini <sstabellini@kernel.org>
>
> v5:
> - Handle the case of xen_feature(XENFEAT_auto_translated_physmap) &&
> (PAGE_SIZE > XEN_PAGE_SIZE)
>
> v4:
> - Remove stray line of debug that causes a build warning on ARM 32-bit
>
> v3:
> - Addres comments from Boris
> - Fix ARM build
>
> v2:
> - Fix bug when mapping multiple pages of a resource
> ---
> arch/arm/xen/enlighten.c | 11 ++++
> arch/x86/xen/mmu.c | 60 +++++++++++++------
> drivers/xen/privcmd.c | 133
> +++++++++++++++++++++++++++++++++++++++++
> include/uapi/xen/privcmd.h | 11 ++++
> include/xen/interface/memory.h | 66 ++++++++++++++++++++
> include/xen/interface/xen.h | 7 ++-
> include/xen/xen-ops.h | 24 +++++++-
> 7 files changed, 291 insertions(+), 21 deletions(-)
>
> diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
> index ba7f4c8f5c3e..8073625371f5 100644
> --- a/arch/arm/xen/enlighten.c
> +++ b/arch/arm/xen/enlighten.c
> @@ -89,6 +89,17 @@ int xen_unmap_domain_gfn_range(struct
> vm_area_struct *vma,
> }
> EXPORT_SYMBOL_GPL(xen_unmap_domain_gfn_range);
>
> +/* Not used by XENFEAT_auto_translated guests. */
> +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)
> +{
> + return -ENOSYS;
> +}
> +EXPORT_SYMBOL_GPL(xen_remap_domain_mfn_array);
> +
> static void xen_read_wallclock(struct timespec64 *ts)
> {
> u32 version;
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index d33e7dbe3129..af2960cb7a3e 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -65,37 +65,44 @@ 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". */
> + /*
> + * If we have a contiguous range, just update the pfn itself,
> + * else update pointer to be "next pfn".
> + */
> 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 +113,14 @@ 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. */
> + /*
> + * We use the err_ptr to indicate if there we are doing a contiguous
> + * mapping or a discontigious mapping.
> + */
> rmd.contiguous = !err_ptr;
> + rmd.no_translate = no_translate;
>
> while (nr) {
> int index = 0;
> @@ -121,7 +131,7 @@ 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 +185,8 @@ 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);
>
> @@ -194,10 +205,25 @@ 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..a7a2286d101a 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 +723,134 @@ 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_fn(pte_t *ptep, pgtable_t token, unsigned long addr,
> + 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)) {
> + unsigned int nr = DIV_ROUND_UP(kdata.num,
> XEN_PFN_PER_PAGE);
> + struct page **pages;
> + unsigned int i;
> +
> + rc = alloc_empty_pages(vma, nr);
> + if (rc < 0)
> + goto out;
> +
> + pages = vma->vm_private_data;
> + for (i = 0; i < kdata.num; i++) {
> + xen_pfn_t pfn =
> + page_to_xen_pfn(pages[i /
> XEN_PFN_PER_PAGE]);
> +
> + pfns[i] = pfn + (i % XEN_PFN_PER_PAGE);
> + }
> + } 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_fn, &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:
> + up_write(&mm->mmap_sem);
> + kfree(pfns);
> +
> + return rc;
> +}
> +
> static long privcmd_ioctl(struct file *file,
> unsigned int cmd, unsigned long data)
> {
> @@ -753,6 +882,10 @@ static long privcmd_ioctl(struct file *file,
> ret = privcmd_ioctl_restrict(file, udata);
> break;
>
> + case IOCTL_PRIVCMD_MMAP_RESOURCE:
> + ret = privcmd_ioctl_mmap_resource(file, udata);
> + break;
> +
> default:
> break;
> }
> diff --git a/include/uapi/xen/privcmd.h b/include/uapi/xen/privcmd.h
> index 39d3e7b8e993..d2029556083e 100644
> --- a/include/uapi/xen/privcmd.h
> +++ b/include/uapi/xen/privcmd.h
> @@ -89,6 +89,15 @@ struct privcmd_dm_op {
> const struct privcmd_dm_op_buf __user *ubufs;
> };
>
> +struct privcmd_mmap_resource {
> + domid_t dom;
> + __u32 type;
> + __u32 id;
> + __u32 idx;
> + __u64 num;
> + __u64 addr;
> +};
> +
> /*
> * @cmd: IOCTL_PRIVCMD_HYPERCALL
> * @arg: &privcmd_hypercall_t
> @@ -114,5 +123,7 @@ struct privcmd_dm_op {
> _IOC(_IOC_NONE, 'P', 5, sizeof(struct privcmd_dm_op))
> #define IOCTL_PRIVCMD_RESTRICT \
> _IOC(_IOC_NONE, 'P', 6, sizeof(domid_t))
> +#define IOCTL_PRIVCMD_MMAP_RESOURCE \
> + _IOC(_IOC_NONE, 'P', 7, sizeof(struct privcmd_mmap_resource))
>
> #endif /* __LINUX_PUBLIC_PRIVCMD_H__ */
> diff --git a/include/xen/interface/memory.h
> b/include/xen/interface/memory.h
> index 583dd93b3016..4c5751c26f87 100644
> --- a/include/xen/interface/memory.h
> +++ b/include/xen/interface/memory.h
> @@ -265,4 +265,70 @@ struct xen_remove_from_physmap {
> };
> DEFINE_GUEST_HANDLE_STRUCT(xen_remove_from_physmap);
>
> +/*
> + * Get the pages for a particular guest resource, so that they can be
> + * mapped directly by a tools domain.
> + */
> +#define XENMEM_acquire_resource 28
> +struct xen_mem_acquire_resource {
> + /* IN - The domain whose resource is to be mapped */
> + domid_t domid;
> + /* IN - the type of resource */
> + uint16_t type;
> +
> +#define XENMEM_resource_ioreq_server 0
> +#define XENMEM_resource_grant_table 1
> +
> + /*
> + * IN - a type-specific resource identifier, which must be zero
> + * unless stated otherwise.
> + *
> + * type == XENMEM_resource_ioreq_server -> id == ioreq server id
> + * type == XENMEM_resource_grant_table -> id defined below
> + */
> + uint32_t id;
> +
> +#define XENMEM_resource_grant_table_id_shared 0
> +#define XENMEM_resource_grant_table_id_status 1
> +
> + /* IN/OUT - As an IN parameter number of frames of the resource
> + * to be mapped. However, if the specified value is 0 and
> + * frame_list is NULL then this field will be set to the
> + * maximum value supported by the implementation on return.
> + */
> + uint32_t nr_frames;
> + /*
> + * OUT - Must be zero on entry. On return this may contain a bitwise
> + * OR of the following values.
> + */
> + uint32_t flags;
> +
> + /* The resource pages have been assigned to the calling domain */
> +#define _XENMEM_rsrc_acq_caller_owned 0
> +#define XENMEM_rsrc_acq_caller_owned (1u <<
> _XENMEM_rsrc_acq_caller_owned)
> +
> + /*
> + * IN - the index of the initial frame to be mapped. This parameter
> + * is ignored if nr_frames is 0.
> + */
> + uint64_t frame;
> +
> +#define XENMEM_resource_ioreq_server_frame_bufioreq 0
> +#define XENMEM_resource_ioreq_server_frame_ioreq(n) (1 + (n))
> +
> + /*
> + * IN/OUT - If the tools domain is PV then, upon return, frame_list
> + * will be populated with the MFNs of the resource.
> + * If the tools domain is HVM then it is expected that, on
> + * entry, frame_list will be populated with a list of GFNs
> + * that will be mapped to the MFNs of the resource.
> + * If -EIO is returned then the frame_list has only been
> + * partially mapped and it is up to the caller to unmap all
> + * the GFNs.
> + * This parameter may be NULL if nr_frames is 0.
> + */
> + GUEST_HANDLE(xen_pfn_t) frame_list;
> +};
> +DEFINE_GUEST_HANDLE_STRUCT(xen_mem_acquire_resource);
> +
> #endif /* __XEN_PUBLIC_MEMORY_H__ */
> diff --git a/include/xen/interface/xen.h b/include/xen/interface/xen.h
> index 4f4830ef8f93..8bfb242f433e 100644
> --- a/include/xen/interface/xen.h
> +++ b/include/xen/interface/xen.h
> @@ -265,9 +265,10 @@
> *
> * PAT (bit 7 on) --> PWT (bit 3 on) and clear bit 7.
> */
> -#define MMU_NORMAL_PT_UPDATE 0 /* checked '*ptr = val'. ptr is MA.
> */
> -#define MMU_MACHPHYS_UPDATE 1 /* ptr = MA of frame to modify
> entry for */
> -#define MMU_PT_UPDATE_PRESERVE_AD 2 /* atomically: *ptr = val |
> (*ptr&(A|D)) */
> +#define MMU_NORMAL_PT_UPDATE 0 /* checked '*ptr = val'. ptr is
> MA. */
> +#define MMU_MACHPHYS_UPDATE 1 /* ptr = MA of frame to modify
> entry for */
> +#define MMU_PT_UPDATE_PRESERVE_AD 2 /* atomically: *ptr = val |
> (*ptr&(A|D)) */
> +#define MMU_PT_UPDATE_NO_TRANSLATE 3 /* checked '*ptr = val'. ptr is
> MA. */
>
> /*
> * MMU EXTENDED OPERATIONS
> diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
> index fd23e42c6024..fd18c974a619 100644
> --- a/include/xen/xen-ops.h
> +++ b/include/xen/xen-ops.h
> @@ -63,7 +63,7 @@ static inline void
> xen_destroy_contiguous_region(phys_addr_t pstart,
> struct vm_area_struct;
>
> /*
> - * xen_remap_domain_gfn_array() - map an array of foreign frames
> + * xen_remap_domain_gfn_array() - map an array of foreign frames by gfn
> * @vma: VMA to map the pages into
> * @addr: Address at which to map the pages
> * @gfn: Array of GFNs to map
> @@ -86,6 +86,28 @@ int xen_remap_domain_gfn_array(struct
> vm_area_struct *vma,
> unsigned domid,
> struct page **pages);
>
> +/*
> + * xen_remap_domain_mfn_array() - map an array of foreign frames by
> mfn
> + * @vma: VMA to map the pages into
> + * @addr: Address at which to map the pages
> + * @mfn: Array of MFNs to map
> + * @nr: Number entries in the MFN array
> + * @err_ptr: Returns per-MFN error status.
> + * @prot: page protection mask
> + * @domid: Domain owning the pages
> + * @pages: Array of pages if this domain has an auto-translated physmap
> + *
> + * @mfn and @err_ptr may point to the same buffer, the MFNs will be
> + * overwritten by the error codes after they are mapped.
> + *
> + * Returns the number of successfully mapped frames, or a -ve error
> + * code.
> + */
> +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);
> +
> /* xen_remap_domain_gfn_range() - map a range of foreign frames
> * @vma: VMA to map the pages into
> * @addr: Address at which to map the pages
> --
> 2.11.0

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