| /* SPDX-License-Identifier: MIT */ |
| |
| /****************************************************************************** |
| * grant_table.h |
| * |
| * Interface for granting foreign access to page frames, and receiving |
| * page-ownership transfers. |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a copy |
| * of this software and associated documentation files (the "Software"), to |
| * deal in the Software without restriction, including without limitation the |
| * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or |
| * sell copies of the Software, and to permit persons to whom the Software is |
| * furnished to do so, subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be included in |
| * all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
| * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
| * DEALINGS IN THE SOFTWARE. |
| * |
| * Copyright (c) 2004, K A Fraser |
| */ |
| |
| #ifndef __XEN_PUBLIC_GRANT_TABLE_H__ |
| #define __XEN_PUBLIC_GRANT_TABLE_H__ |
| |
| #include "xen.h" |
| |
| /* |
| * `incontents 150 gnttab Grant Tables |
| * |
| * Xen's grant tables provide a generic mechanism to memory sharing |
| * between domains. This shared memory interface underpins the split |
| * device drivers for block and network IO. |
| * |
| * Each domain has its own grant table. This is a data structure that |
| * is shared with Xen; it allows the domain to tell Xen what kind of |
| * permissions other domains have on its pages. Entries in the grant |
| * table are identified by grant references. A grant reference is an |
| * integer, which indexes into the grant table. It acts as a |
| * capability which the grantee can use to perform operations on the |
| * granter's memory. |
| * |
| * This capability-based system allows shared-memory communications |
| * between unprivileged domains. A grant reference also encapsulates |
| * the details of a shared page, removing the need for a domain to |
| * know the real machine address of a page it is sharing. This makes |
| * it possible to share memory correctly with domains running in |
| * fully virtualised memory. |
| */ |
| |
| /*********************************** |
| * GRANT TABLE REPRESENTATION |
| */ |
| |
| /* Some rough guidelines on accessing and updating grant-table entries |
| * in a concurrency-safe manner. For more information, Linux contains a |
| * reference implementation for guest OSes (drivers/xen/grant_table.c, see |
| * http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=drivers/xen/grant-table.c;hb=HEAD |
| * |
| * NB. WMB is a no-op on current-generation x86 processors. However, a |
| * compiler barrier will still be required. |
| * |
| * Introducing a valid entry into the grant table: |
| * 1. Write ent->domid. |
| * 2. Write ent->frame: |
| * GTF_permit_access: Frame to which access is permitted. |
| * GTF_accept_transfer: Pseudo-phys frame slot being filled by new |
| * frame, or zero if none. |
| * 3. Write memory barrier (WMB). |
| * 4. Write ent->flags, inc. valid type. |
| * |
| * Invalidating an unused GTF_permit_access entry: |
| * 1. flags = ent->flags. |
| * 2. Observe that !(flags & (GTF_reading|GTF_writing)). |
| * 3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0). |
| * NB. No need for WMB as reuse of entry is control-dependent on success of |
| * step 3, and all architectures guarantee ordering of ctrl-dep writes. |
| * |
| * Invalidating an in-use GTF_permit_access entry: |
| * This cannot be done directly. Request assistance from the domain controller |
| * which can set a timeout on the use of a grant entry and take necessary |
| * action. (NB. This is not yet implemented!). |
| * |
| * Invalidating an unused GTF_accept_transfer entry: |
| * 1. flags = ent->flags. |
| * 2. Observe that !(flags & GTF_transfer_committed). [*] |
| * 3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0). |
| * NB. No need for WMB as reuse of entry is control-dependent on success of |
| * step 3, and all architectures guarantee ordering of ctrl-dep writes. |
| * [*] If GTF_transfer_committed is set then the grant entry is 'committed'. |
| * The guest must /not/ modify the grant entry until the address of the |
| * transferred frame is written. It is safe for the guest to spin waiting |
| * for this to occur (detect by observing GTF_transfer_completed in |
| * ent->flags). |
| * |
| * Invalidating a committed GTF_accept_transfer entry: |
| * 1. Wait for (ent->flags & GTF_transfer_completed). |
| * |
| * Changing a GTF_permit_access from writable to read-only: |
| * Use SMP-safe CMPXCHG to set GTF_readonly, while checking !GTF_writing. |
| * |
| * Changing a GTF_permit_access from read-only to writable: |
| * Use SMP-safe bit-setting instruction. |
| */ |
| |
| /* |
| * Reference to a grant entry in a specified domain's grant table. |
| */ |
| typedef uint32_t grant_ref_t; |
| |
| /* |
| * A grant table comprises a packed array of grant entries in one or more |
| * page frames shared between Xen and a guest. |
| * [XEN]: This field is written by Xen and read by the sharing guest. |
| * [GST]: This field is written by the guest and read by Xen. |
| */ |
| |
| /* |
| * Version 1 of the grant table entry structure is maintained purely |
| * for backwards compatibility. New guests should use version 2. |
| */ |
| #if __XEN_INTERFACE_VERSION__ < 0x0003020a |
| #define grant_entry_v1 grant_entry |
| #define grant_entry_v1_t grant_entry_t |
| #endif |
| struct grant_entry_v1 { |
| /* GTF_xxx: various type and flag information. [XEN,GST] */ |
| uint16_t flags; |
| /* The domain being granted foreign privileges. [GST] */ |
| domid_t domid; |
| /* |
| * GTF_permit_access: GFN that @domid is allowed to map and access. [GST] |
| * GTF_accept_transfer: GFN that @domid is allowed to transfer into. [GST] |
| * GTF_transfer_completed: MFN whose ownership transferred by @domid |
| * (non-translated guests only). [XEN] |
| */ |
| uint32_t frame; |
| }; |
| typedef struct grant_entry_v1 grant_entry_v1_t; |
| |
| /* The first few grant table entries will be preserved across grant table |
| * version changes and may be pre-populated at domain creation by tools. |
| */ |
| #define GNTTAB_NR_RESERVED_ENTRIES 8 |
| #define GNTTAB_RESERVED_CONSOLE 0 |
| #define GNTTAB_RESERVED_XENSTORE 1 |
| |
| /* |
| * Type of grant entry. |
| * GTF_invalid: This grant entry grants no privileges. |
| * GTF_permit_access: Allow @domid to map/access @frame. |
| * GTF_accept_transfer: Allow @domid to transfer ownership of one page frame |
| * to this guest. Xen writes the page number to @frame. |
| * GTF_transitive: Allow @domid to transitively access a subrange of |
| * @trans_grant in @trans_domid. No mappings are allowed. |
| */ |
| #define GTF_invalid (0U << 0) |
| #define GTF_permit_access (1U << 0) |
| #define GTF_accept_transfer (2U << 0) |
| #define GTF_transitive (3U << 0) |
| #define GTF_type_mask (3U << 0) |
| |
| /* |
| * Subflags for GTF_permit_access and GTF_transitive. |
| * GTF_readonly: Restrict @domid to read-only mappings and accesses. [GST] |
| * GTF_reading: Grant entry is currently mapped for reading by @domid. [XEN] |
| * GTF_writing: Grant entry is currently mapped for writing by @domid. [XEN] |
| * Further subflags for GTF_permit_access only. |
| * GTF_PAT, GTF_PWT, GTF_PCD: (x86) cache attribute flags to be used for |
| * mappings of the grant [GST] |
| * GTF_sub_page: Grant access to only a subrange of the page. @domid |
| * will only be allowed to copy from the grant, and not |
| * map it. [GST] |
| */ |
| #define _GTF_readonly (2) |
| #define GTF_readonly (1U << _GTF_readonly) |
| #define _GTF_reading (3) |
| #define GTF_reading (1U << _GTF_reading) |
| #define _GTF_writing (4) |
| #define GTF_writing (1U << _GTF_writing) |
| #define _GTF_PWT (5) |
| #define GTF_PWT (1U << _GTF_PWT) |
| #define _GTF_PCD (6) |
| #define GTF_PCD (1U << _GTF_PCD) |
| #define _GTF_PAT (7) |
| #define GTF_PAT (1U << _GTF_PAT) |
| #define _GTF_sub_page (8) |
| #define GTF_sub_page (1U << _GTF_sub_page) |
| |
| /* |
| * Subflags for GTF_accept_transfer: |
| * GTF_transfer_committed: Xen sets this flag to indicate that it is committed |
| * to transferring ownership of a page frame. When a guest sees this flag |
| * it must /not/ modify the grant entry until GTF_transfer_completed is |
| * set by Xen. |
| * GTF_transfer_completed: It is safe for the guest to spin-wait on this flag |
| * after reading GTF_transfer_committed. Xen will always write the frame |
| * address, followed by ORing this flag, in a timely manner. |
| */ |
| #define _GTF_transfer_committed (2) |
| #define GTF_transfer_committed (1U << _GTF_transfer_committed) |
| #define _GTF_transfer_completed (3) |
| #define GTF_transfer_completed (1U << _GTF_transfer_completed) |
| |
| /*********************************** |
| * GRANT TABLE QUERIES AND USES |
| */ |
| |
| /* ` enum neg_errnoval |
| * ` HYPERVISOR_grant_table_op(enum grant_table_op cmd, |
| * ` void *args, |
| * ` unsigned int count) |
| * ` |
| * |
| * @args points to an array of a per-command data structure. The array |
| * has @count members |
| */ |
| |
| /* ` enum grant_table_op { // GNTTABOP_* => struct gnttab_* */ |
| #define GNTTABOP_map_grant_ref 0 |
| #define GNTTABOP_unmap_grant_ref 1 |
| #define GNTTABOP_setup_table 2 |
| #define GNTTABOP_dump_table 3 |
| #define GNTTABOP_transfer 4 |
| #define GNTTABOP_copy 5 |
| #define GNTTABOP_query_size 6 |
| #define GNTTABOP_unmap_and_replace 7 |
| #if __XEN_INTERFACE_VERSION__ >= 0x0003020a |
| #define GNTTABOP_set_version 8 |
| #define GNTTABOP_get_status_frames 9 |
| #define GNTTABOP_get_version 10 |
| #define GNTTABOP_swap_grant_ref 11 |
| #define GNTTABOP_cache_flush 12 |
| #endif /* __XEN_INTERFACE_VERSION__ */ |
| /* ` } */ |
| |
| /* |
| * Handle to track a mapping created via a grant reference. |
| */ |
| typedef uint32_t grant_handle_t; |
| |
| /* |
| * GNTTABOP_map_grant_ref: Map the grant entry (<dom>,<ref>) for access |
| * by devices and/or host CPUs. If successful, <handle> is a tracking number |
| * that must be presented later to destroy the mapping(s). On error, <status> |
| * is a negative status code. |
| * NOTES: |
| * 1. If GNTMAP_device_map is specified then <dev_bus_addr> is the address |
| * via which I/O devices may access the granted frame. |
| * 2. If GNTMAP_host_map is specified then a mapping will be added at |
| * either a host virtual address in the current address space, or at |
| * a PTE at the specified machine address. The type of mapping to |
| * perform is selected through the GNTMAP_contains_pte flag, and the |
| * address is specified in <host_addr>. |
| * 3. Mappings should only be destroyed via GNTTABOP_unmap_grant_ref. If a |
| * host mapping is destroyed by other means then it is *NOT* guaranteed |
| * to be accounted to the correct grant reference! |
| */ |
| struct gnttab_map_grant_ref { |
| /* IN parameters. */ |
| uint64_t host_addr; |
| uint32_t flags; /* GNTMAP_* */ |
| grant_ref_t ref; |
| domid_t dom; |
| /* OUT parameters. */ |
| int16_t status; /* => enum grant_status */ |
| grant_handle_t handle; |
| uint64_t dev_bus_addr; |
| }; |
| typedef struct gnttab_map_grant_ref gnttab_map_grant_ref_t; |
| DEFINE_XEN_GUEST_HANDLE(gnttab_map_grant_ref_t); |
| |
| /* |
| * GNTTABOP_unmap_grant_ref: Destroy one or more grant-reference mappings |
| * tracked by <handle>. If <host_addr> or <dev_bus_addr> is zero, that |
| * field is ignored. If non-zero, they must refer to a device/host mapping |
| * that is tracked by <handle> |
| * NOTES: |
| * 1. The call may fail in an undefined manner if either mapping is not |
| * tracked by <handle>. |
| * 3. After executing a batch of unmaps, it is guaranteed that no stale |
| * mappings will remain in the device or host TLBs. |
| */ |
| struct gnttab_unmap_grant_ref { |
| /* IN parameters. */ |
| uint64_t host_addr; |
| uint64_t dev_bus_addr; |
| grant_handle_t handle; |
| /* OUT parameters. */ |
| int16_t status; /* => enum grant_status */ |
| }; |
| typedef struct gnttab_unmap_grant_ref gnttab_unmap_grant_ref_t; |
| DEFINE_XEN_GUEST_HANDLE(gnttab_unmap_grant_ref_t); |
| |
| /* |
| * GNTTABOP_setup_table: Set up a grant table for <dom> comprising at least |
| * <nr_frames> pages. The frame addresses are written to the <frame_list>. |
| * Only <nr_frames> addresses are written, even if the table is larger. |
| * NOTES: |
| * 1. <dom> may be specified as DOMID_SELF. |
| * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF. |
| * 3. Xen may not support more than a single grant-table page per domain. |
| */ |
| struct gnttab_setup_table { |
| /* IN parameters. */ |
| domid_t dom; |
| uint32_t nr_frames; |
| |
| /* OUT parameters. */ |
| int16_t status; /* => enum grant_status */ |
| #if __XEN_INTERFACE_VERSION__ < 0x00040300 |
| XEN_GUEST_HANDLE(ulong) frame_list; |
| #else |
| XEN_GUEST_HANDLE(xen_pfn_t) frame_list; |
| #endif |
| }; |
| typedef struct gnttab_setup_table gnttab_setup_table_t; |
| DEFINE_XEN_GUEST_HANDLE(gnttab_setup_table_t); |
| |
| |
| |
| /* |
| * Bitfield values for gnttab_map_grant_ref.flags. |
| */ |
| /* Map the grant entry for access by I/O devices. */ |
| #define _GNTMAP_device_map (0) |
| #define GNTMAP_device_map (1<<_GNTMAP_device_map) |
| /* Map the grant entry for access by host CPUs. */ |
| #define _GNTMAP_host_map (1) |
| #define GNTMAP_host_map (1<<_GNTMAP_host_map) |
| /* Accesses to the granted frame will be restricted to read-only access. */ |
| #define _GNTMAP_readonly (2) |
| #define GNTMAP_readonly (1<<_GNTMAP_readonly) |
| /* |
| * GNTMAP_host_map subflag: |
| * 0 => The host mapping is usable only by the guest OS. |
| * 1 => The host mapping is usable by guest OS + current application. |
| */ |
| #define _GNTMAP_application_map (3) |
| #define GNTMAP_application_map (1<<_GNTMAP_application_map) |
| |
| /* |
| * GNTMAP_contains_pte subflag: |
| * 0 => This map request contains a host virtual address. |
| * 1 => This map request contains the machine addess of the PTE to update. |
| */ |
| #define _GNTMAP_contains_pte (4) |
| #define GNTMAP_contains_pte (1<<_GNTMAP_contains_pte) |
| |
| /* |
| * Bits to be placed in guest kernel available PTE bits (architecture |
| * dependent; only supported when XENFEAT_gnttab_map_avail_bits is set). |
| */ |
| #define _GNTMAP_guest_avail0 (16) |
| #define GNTMAP_guest_avail_mask ((uint32_t)~0 << _GNTMAP_guest_avail0) |
| |
| /* |
| * Values for error status returns. All errors are -ve. |
| */ |
| /* ` enum grant_status { */ |
| #define GNTST_okay (0) /* Normal return */ |
| #define GNTST_general_error (-1) /* General undefined error */ |
| #define GNTST_bad_domain (-2) /* Unrecognsed domain id */ |
| #define GNTST_bad_gntref (-3) /* Unrecognised or inappropriate gntref */ |
| #define GNTST_bad_handle (-4) /* Unrecognised or inappropriate handle */ |
| #define GNTST_bad_virt_addr (-5) /* Inappropriate virtual address to map */ |
| #define GNTST_bad_dev_addr (-6) /* Inappropriate device address to unmap */ |
| #define GNTST_no_device_space (-7) /* Out of space in I/O MMU */ |
| #define GNTST_permission_denied (-8) /* Not enough privilege for operation */ |
| #define GNTST_bad_page (-9) /* Specified page was invalid for op */ |
| #define GNTST_bad_copy_arg (-10) /* copy arguments cross page boundary */ |
| #define GNTST_address_too_big (-11) /* transfer page address too large */ |
| #define GNTST_eagain (-12) /* Operation not done; try agains */ |
| /* ` } */ |
| |
| #define GNTTABOP_error_msgs { \ |
| "okay", \ |
| "undefined error", \ |
| "unrecognised domain id", \ |
| "invalid grant reference", \ |
| "invalid mapping handle", \ |
| "invalid virtual address", \ |
| "invalid device address", \ |
| "no spare translation slot in the I/O MMU", \ |
| "permission denied", \ |
| "bad page", \ |
| "copy arguments cross page boundary", \ |
| "page address size too large", \ |
| "operation not done; try again" \ |
| } |
| |
| #endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */ |