On Tue, 12 Jan 2021, Oleksandr Tyshchenko wrote:
> From: Julien Grall <[email protected]>
>
> This patch adds basic IOREQ/DM support on Arm. The subsequent
> patches will improve functionality and add remaining bits.
>
> The IOREQ/DM features are supposed to be built with IOREQ_SERVER
> option enabled, which is disabled by default on Arm for now.
>
> Please note, the "PIO handling" TODO is expected to left unaddressed
> for the current series. It is not an big issue for now while Xen
> doesn't have support for vPCI on Arm. On Arm64 they are only used
> for PCI IO Bar and we would probably want to expose them to emulator
> as PIO access to make a DM completely arch-agnostic. So "PIO handling"
> should be implemented when we add support for vPCI.
>
> Signed-off-by: Julien Grall <[email protected]>
> Signed-off-by: Oleksandr Tyshchenko <[email protected]>
> [On Arm only]
> Tested-by: Wei Chen <[email protected]>
>
> ---
> Please note, this is a split/cleanup/hardening of Julien's PoC:
> "Add support for Guest IO forwarding to a device emulator"
>
> Changes RFC -> V1:
> - was split into:
> - arm/ioreq: Introduce arch specific bits for IOREQ/DM features
> - xen/mm: Handle properly reference in set_foreign_p2m_entry() on Arm
> - update patch description
> - update asm-arm/hvm/ioreq.h according to the newly introduced arch
> functions:
> - arch_hvm_destroy_ioreq_server()
> - arch_handle_hvm_io_completion()
> - update arch files to include xen/ioreq.h
> - remove HVMOP plumbing
> - rewrite a logic to handle properly case when hvm_send_ioreq() returns
> IO_RETRY
> - add a logic to handle properly handle_hvm_io_completion() return value
> - rename handle_mmio() to ioreq_handle_complete_mmio()
> - move paging_mark_pfn_dirty() to asm-arm/paging.h
> - remove forward declaration for hvm_ioreq_server in asm-arm/paging.h
> - move try_fwd_ioserv() to ioreq.c, provide stubs if !CONFIG_IOREQ_SERVER
> - do not remove #ifdef CONFIG_IOREQ_SERVER in memory.c for guarding
> xen/ioreq.h
> - use gdprintk in try_fwd_ioserv(), remove unneeded prints
> - update list of #include-s
> - move has_vpci() to asm-arm/domain.h
> - add a comment (TODO) to unimplemented yet handle_pio()
> - remove hvm_mmio_first(last)_byte() and hvm_ioreq_(page/vcpu/server)
> structs
> from the arch files, they were already moved to the common code
> - remove set_foreign_p2m_entry() changes, they will be properly implemented
> in the follow-up patch
> - select IOREQ_SERVER for Arm instead of Arm64 in Kconfig
> - remove x86's realmode and other unneeded stubs from xen/ioreq.h
> - clafify ioreq_t p.df usage in try_fwd_ioserv()
> - set ioreq_t p.count to 1 in try_fwd_ioserv()
>
> Changes V1 -> V2:
> - was split into:
> - arm/ioreq: Introduce arch specific bits for IOREQ/DM features
> - xen/arm: Stick around in leave_hypervisor_to_guest until I/O has
> completed
> - update the author of a patch
> - update patch description
> - move a loop in leave_hypervisor_to_guest() to a separate patch
> - set IOREQ_SERVER disabled by default
> - remove already clarified /* XXX */
> - replace BUG() by ASSERT_UNREACHABLE() in handle_pio()
> - remove default case for handling the return value of try_handle_mmio()
> - remove struct hvm_domain, enum hvm_io_completion, struct hvm_vcpu_io,
> struct hvm_vcpu from asm-arm/domain.h, these are common materials now
> - update everything according to the recent changes (IOREQ related function
> names don't contain "hvm" prefixes/infixes anymore, IOREQ related fields
> are part of common struct vcpu/domain now, etc)
>
> Changes V2 -> V3:
> - update patch according the "legacy interface" is x86 specific
> - add dummy arch hooks
> - remove dummy paging_mark_pfn_dirty()
> - don’t include <xen/domain_page.h> in common ioreq.c
> - don’t include <public/hvm/ioreq.h> in arch ioreq.h
> - remove #define ioreq_params(d, i)
>
> Changes V3 -> V4:
> - rebase
> - update patch according to the renaming IO_ -> VIO_ (io_ -> vio_)
> and misc changes to arch hooks
> - update patch according to the IOREQ related dm-op handling changes
> - don't include <xen/ioreq.h> from arch header
> - make all arch hooks out-of-line
> - add a comment above IOREQ_STATUS_* #define-s
> ---
> xen/arch/arm/Makefile | 2 +
> xen/arch/arm/dm.c | 122 +++++++++++++++++++++++
> xen/arch/arm/domain.c | 9 ++
> xen/arch/arm/io.c | 12 ++-
> xen/arch/arm/ioreq.c | 213
> ++++++++++++++++++++++++++++++++++++++++
> xen/arch/arm/traps.c | 13 +++
> xen/include/asm-arm/domain.h | 3 +
> xen/include/asm-arm/hvm/ioreq.h | 72 ++++++++++++++
> xen/include/asm-arm/mmio.h | 1 +
> 9 files changed, 446 insertions(+), 1 deletion(-)
> create mode 100644 xen/arch/arm/dm.c
> create mode 100644 xen/arch/arm/ioreq.c
> create mode 100644 xen/include/asm-arm/hvm/ioreq.h
>
> diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
> index 512ffdd..16e6523 100644
> --- a/xen/arch/arm/Makefile
> +++ b/xen/arch/arm/Makefile
> @@ -13,6 +13,7 @@ obj-y += cpuerrata.o
> obj-y += cpufeature.o
> obj-y += decode.o
> obj-y += device.o
> +obj-$(CONFIG_IOREQ_SERVER) += dm.o
> obj-y += domain.o
> obj-y += domain_build.init.o
> obj-y += domctl.o
> @@ -27,6 +28,7 @@ obj-y += guest_atomics.o
> obj-y += guest_walk.o
> obj-y += hvm.o
> obj-y += io.o
> +obj-$(CONFIG_IOREQ_SERVER) += ioreq.o
> obj-y += irq.o
> obj-y += kernel.init.o
> obj-$(CONFIG_LIVEPATCH) += livepatch.o
> diff --git a/xen/arch/arm/dm.c b/xen/arch/arm/dm.c
> new file mode 100644
> index 0000000..e6dedf4
> --- /dev/null
> +++ b/xen/arch/arm/dm.c
> @@ -0,0 +1,122 @@
> +/*
> + * Copyright (c) 2019 Arm ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along
> with
> + * this program; If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <xen/dm.h>
> +#include <xen/guest_access.h>
> +#include <xen/hypercall.h>
> +#include <xen/ioreq.h>
> +#include <xen/nospec.h>
> +
> +static int dm_op(const struct dmop_args *op_args)
> +{
> + struct domain *d;
> + struct xen_dm_op op;
> + bool const_op = true;
> + long rc;
> + size_t offset;
> +
> + static const uint8_t op_size[] = {
> + [XEN_DMOP_create_ioreq_server] = sizeof(struct
> xen_dm_op_create_ioreq_server),
> + [XEN_DMOP_get_ioreq_server_info] = sizeof(struct
> xen_dm_op_get_ioreq_server_info),
> + [XEN_DMOP_map_io_range_to_ioreq_server] = sizeof(struct
> xen_dm_op_ioreq_server_range),
> + [XEN_DMOP_unmap_io_range_from_ioreq_server] = sizeof(struct
> xen_dm_op_ioreq_server_range),
> + [XEN_DMOP_set_ioreq_server_state] = sizeof(struct
> xen_dm_op_set_ioreq_server_state),
> + [XEN_DMOP_destroy_ioreq_server] = sizeof(struct
> xen_dm_op_destroy_ioreq_server),
> + };
> +
> + rc = rcu_lock_remote_domain_by_id(op_args->domid, &d);
> + if ( rc )
> + return rc;
> +
> + rc = xsm_dm_op(XSM_DM_PRIV, d);
> + if ( rc )
> + goto out;
> +
> + offset = offsetof(struct xen_dm_op, u);
> +
> + rc = -EFAULT;
> + if ( op_args->buf[0].size < offset )
> + goto out;
> +
> + if ( copy_from_guest_offset((void *)&op, op_args->buf[0].h, 0, offset) )
> + goto out;
> +
> + if ( op.op >= ARRAY_SIZE(op_size) )
> + {
> + rc = -EOPNOTSUPP;
> + goto out;
> + }
> +
> + op.op = array_index_nospec(op.op, ARRAY_SIZE(op_size));
> +
> + if ( op_args->buf[0].size < offset + op_size[op.op] )
> + goto out;
> +
> + if ( copy_from_guest_offset((void *)&op.u, op_args->buf[0].h, offset,
> + op_size[op.op]) )
> + goto out;
> +
> + rc = -EINVAL;
> + if ( op.pad )
> + goto out;
> +
> + rc = ioreq_server_dm_op(&op, d, &const_op);
> +
> + if ( (!rc || rc == -ERESTART) &&
> + !const_op && copy_to_guest_offset(op_args->buf[0].h, offset,
> + (void *)&op.u, op_size[op.op]) )
> + rc = -EFAULT;
> +
> + out:
> + rcu_unlock_domain(d);
> +
> + return rc;
> +}
> +
> +long do_dm_op(domid_t domid,
> + unsigned int nr_bufs,
> + XEN_GUEST_HANDLE_PARAM(xen_dm_op_buf_t) bufs)
> +{
> + struct dmop_args args;
> + int rc;
> +
> + if ( nr_bufs > ARRAY_SIZE(args.buf) )
> + return -E2BIG;
> +
> + args.domid = domid;
> + args.nr_bufs = array_index_nospec(nr_bufs, ARRAY_SIZE(args.buf) + 1);
> +
> + if ( copy_from_guest_offset(&args.buf[0], bufs, 0, args.nr_bufs) )
> + return -EFAULT;
> +
> + rc = dm_op(&args);
> +
> + if ( rc == -ERESTART )
> + rc = hypercall_create_continuation(__HYPERVISOR_dm_op, "iih",
> + domid, nr_bufs, bufs);
> +
> + return rc;
> +}
I might have missed something in the discussions but this function is
identical to xen/arch/x86/hvm/dm.c:do_dm_op, why not make it common?
Also the previous function dm_op is very similar to
xen/arch/x86/hvm/dm.c:dm_op I would prefer to make them common if
possible. Was this already discussed?
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * tab-width: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
> index 18cafcd..8f55aba 100644
> --- a/xen/arch/arm/domain.c
> +++ b/xen/arch/arm/domain.c
> @@ -15,6 +15,7 @@
> #include <xen/guest_access.h>
> #include <xen/hypercall.h>
> #include <xen/init.h>
> +#include <xen/ioreq.h>
> #include <xen/lib.h>
> #include <xen/livepatch.h>
> #include <xen/sched.h>
> @@ -696,6 +697,10 @@ int arch_domain_create(struct domain *d,
>
> ASSERT(config != NULL);
>
> +#ifdef CONFIG_IOREQ_SERVER
> + ioreq_domain_init(d);
> +#endif
> +
> /* p2m_init relies on some value initialized by the IOMMU subsystem */
> if ( (rc = iommu_domain_init(d, config->iommu_opts)) != 0 )
> goto fail;
> @@ -1014,6 +1019,10 @@ int domain_relinquish_resources(struct domain *d)
> if (ret )
> return ret;
>
> +#ifdef CONFIG_IOREQ_SERVER
> + ioreq_server_destroy_all(d);
> +#endif
> +
> PROGRESS(xen):
> ret = relinquish_memory(d, &d->xenpage_list);
> if ( ret )
> diff --git a/xen/arch/arm/io.c b/xen/arch/arm/io.c
> index ae7ef96..9814481 100644
> --- a/xen/arch/arm/io.c
> +++ b/xen/arch/arm/io.c
> @@ -16,6 +16,7 @@
> * GNU General Public License for more details.
> */
>
> +#include <xen/ioreq.h>
> #include <xen/lib.h>
> #include <xen/spinlock.h>
> #include <xen/sched.h>
> @@ -23,6 +24,7 @@
> #include <asm/cpuerrata.h>
> #include <asm/current.h>
> #include <asm/mmio.h>
> +#include <asm/hvm/ioreq.h>
>
> #include "decode.h"
>
> @@ -123,7 +125,15 @@ enum io_state try_handle_mmio(struct cpu_user_regs *regs,
>
> handler = find_mmio_handler(v->domain, info.gpa);
> if ( !handler )
> - return IO_UNHANDLED;
> + {
> + int rc;
> +
> + rc = try_fwd_ioserv(regs, v, &info);
> + if ( rc == IO_HANDLED )
> + return handle_ioserv(regs, v);
> +
> + return rc;
> + }
>
> /* All the instructions used on emulated MMIO region should be valid */
> if ( !dabt.valid )
> diff --git a/xen/arch/arm/ioreq.c b/xen/arch/arm/ioreq.c
> new file mode 100644
> index 0000000..3c4a24d
> --- /dev/null
> +++ b/xen/arch/arm/ioreq.c
> @@ -0,0 +1,213 @@
> +/*
> + * arm/ioreq.c: hardware virtual machine I/O emulation
> + *
> + * Copyright (c) 2019 Arm ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along
> with
> + * this program; If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <xen/domain.h>
> +#include <xen/ioreq.h>
> +
> +#include <asm/traps.h>
> +
> +#include <public/hvm/ioreq.h>
> +
> +enum io_state handle_ioserv(struct cpu_user_regs *regs, struct vcpu *v)
> +{
> + const union hsr hsr = { .bits = regs->hsr };
> + const struct hsr_dabt dabt = hsr.dabt;
> + /* Code is similar to handle_read */
> + uint8_t size = (1 << dabt.size) * 8;
> + register_t r = v->io.req.data;
> +
> + /* We are done with the IO */
> + v->io.req.state = STATE_IOREQ_NONE;
> +
> + if ( dabt.write )
> + return IO_HANDLED;
> +
> + /*
> + * Sign extend if required.
> + * Note that we expect the read handler to have zeroed the bits
> + * outside the requested access size.
> + */
> + if ( dabt.sign && (r & (1UL << (size - 1))) )
> + {
> + /*
> + * We are relying on register_t using the same as
> + * an unsigned long in order to keep the 32-bit assembly
> + * code smaller.
> + */
> + BUILD_BUG_ON(sizeof(register_t) != sizeof(unsigned long));
> + r |= (~0UL) << size;
> + }
> +
> + set_user_reg(regs, dabt.reg, r);
> +
> + return IO_HANDLED;
> +}
> +
> +enum io_state try_fwd_ioserv(struct cpu_user_regs *regs,
> + struct vcpu *v, mmio_info_t *info)
> +{
> + struct vcpu_io *vio = &v->io;
> + ioreq_t p = {
> + .type = IOREQ_TYPE_COPY,
> + .addr = info->gpa,
> + .size = 1 << info->dabt.size,
> + .count = 1,
> + .dir = !info->dabt.write,
> + /*
> + * On x86, df is used by 'rep' instruction to tell the direction
> + * to iterate (forward or backward).
> + * On Arm, all the accesses to MMIO region will do a single
> + * memory access. So for now, we can safely always set to 0.
> + */
> + .df = 0,
> + .data = get_user_reg(regs, info->dabt.reg),
> + .state = STATE_IOREQ_READY,
> + };
> + struct ioreq_server *s = NULL;
> + enum io_state rc;
> +
> + switch ( vio->req.state )
> + {
> + case STATE_IOREQ_NONE:
> + break;
> +
> + case STATE_IORESP_READY:
> + return IO_HANDLED;
> +
> + default:
> + gdprintk(XENLOG_ERR, "wrong state %u\n", vio->req.state);
> + return IO_ABORT;
> + }
> +
> + s = ioreq_server_select(v->domain, &p);
> + if ( !s )
> + return IO_UNHANDLED;
> +
> + if ( !info->dabt.valid )
> + return IO_ABORT;
> +
> + vio->req = p;
> +
> + rc = ioreq_send(s, &p, 0);
> + if ( rc != IO_RETRY || v->domain->is_shutting_down )
> + vio->req.state = STATE_IOREQ_NONE;
> + else if ( !ioreq_needs_completion(&vio->req) )
> + rc = IO_HANDLED;
> + else
> + vio->completion = VIO_mmio_completion;
> +
> + return rc;
> +}
> +
> +bool arch_ioreq_complete_mmio(void)
> +{
> + struct vcpu *v = current;
> + struct cpu_user_regs *regs = guest_cpu_user_regs();
> + const union hsr hsr = { .bits = regs->hsr };
> + paddr_t addr = v->io.req.addr;
> +
> + if ( try_handle_mmio(regs, hsr, addr) == IO_HANDLED )
> + {
> + advance_pc(regs, hsr);
> + return true;
> + }
> +
> + return false;
> +}
> +
> +bool arch_vcpu_ioreq_completion(enum vio_completion completion)
> +{
> + ASSERT_UNREACHABLE();
> + return true;
> +}
> +
> +/*
> + * The "legacy" mechanism of mapping magic pages for the IOREQ servers
> + * is x86 specific, so the following hooks don't need to be implemented on
> Arm:
> + * - arch_ioreq_server_map_pages
> + * - arch_ioreq_server_unmap_pages
> + * - arch_ioreq_server_enable
> + * - arch_ioreq_server_disable
> + */
> +int arch_ioreq_server_map_pages(struct ioreq_server *s)
> +{
> + return -EOPNOTSUPP;
> +}
> +
> +void arch_ioreq_server_unmap_pages(struct ioreq_server *s)
> +{
> +}
> +
> +void arch_ioreq_server_enable(struct ioreq_server *s)
> +{
> +}
> +
> +void arch_ioreq_server_disable(struct ioreq_server *s)
> +{
> +}
> +
> +void arch_ioreq_server_destroy(struct ioreq_server *s)
> +{
> +}
> +
> +int arch_ioreq_server_map_mem_type(struct domain *d,
> + struct ioreq_server *s,
> + uint32_t flags)
> +{
> + return -EOPNOTSUPP;
> +}
> +
> +void arch_ioreq_server_map_mem_type_completed(struct domain *d,
> + struct ioreq_server *s,
> + uint32_t flags)
> +{
> +}
> +
> +bool arch_ioreq_server_destroy_all(struct domain *d)
> +{
> + return true;
> +}
> +
> +bool arch_ioreq_server_get_type_addr(const struct domain *d,
> + const ioreq_t *p,
> + uint8_t *type,
> + uint64_t *addr)
> +{
> + if ( p->type != IOREQ_TYPE_COPY && p->type != IOREQ_TYPE_PIO )
> + return false;
> +
> + *type = (p->type == IOREQ_TYPE_PIO) ?
> + XEN_DMOP_IO_RANGE_PORT : XEN_DMOP_IO_RANGE_MEMORY;
> + *addr = p->addr;
> +
> + return true;
> +}
> +
> +void arch_ioreq_domain_init(struct domain *d)
> +{
> +}
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * tab-width: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
> index 22bd1bd..036b13f 100644
> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -21,6 +21,7 @@
> #include <xen/hypercall.h>
> #include <xen/init.h>
> #include <xen/iocap.h>
> +#include <xen/ioreq.h>
> #include <xen/irq.h>
> #include <xen/lib.h>
> #include <xen/mem_access.h>
> @@ -1385,6 +1386,9 @@ static arm_hypercall_t arm_hypercall_table[] = {
> #ifdef CONFIG_HYPFS
> HYPERCALL(hypfs_op, 5),
> #endif
> +#ifdef CONFIG_IOREQ_SERVER
> + HYPERCALL(dm_op, 3),
> +#endif
> };
>
> #ifndef NDEBUG
> @@ -1956,6 +1960,9 @@ static void do_trap_stage2_abort_guest(struct
> cpu_user_regs *regs,
> case IO_HANDLED:
> advance_pc(regs, hsr);
> return;
> + case IO_RETRY:
> + /* finish later */
> + return;
> case IO_UNHANDLED:
> /* IO unhandled, try another way to handle it. */
> break;
> @@ -2254,6 +2261,12 @@ static void check_for_vcpu_work(void)
> {
> struct vcpu *v = current;
>
> +#ifdef CONFIG_IOREQ_SERVER
> + local_irq_enable();
> + vcpu_ioreq_handle_completion(v);
> + local_irq_disable();
> +#endif
> +
> if ( likely(!v->arch.need_flush_to_ram) )
> return;
>
> diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
> index 6819a3b..c235e5b 100644
> --- a/xen/include/asm-arm/domain.h
> +++ b/xen/include/asm-arm/domain.h
> @@ -10,6 +10,7 @@
> #include <asm/gic.h>
> #include <asm/vgic.h>
> #include <asm/vpl011.h>
> +#include <public/hvm/dm_op.h>
> #include <public/hvm/params.h>
>
> struct hvm_domain
> @@ -262,6 +263,8 @@ static inline void arch_vcpu_block(struct vcpu *v) {}
>
> #define arch_vm_assist_valid_mask(d) (1UL <<
> VMASST_TYPE_runstate_update_flag)
>
> +#define has_vpci(d) ({ (void)(d); false; })
> +
> #endif /* __ASM_DOMAIN_H__ */
>
> /*
> diff --git a/xen/include/asm-arm/hvm/ioreq.h b/xen/include/asm-arm/hvm/ioreq.h
> new file mode 100644
> index 0000000..19e1247
> --- /dev/null
> +++ b/xen/include/asm-arm/hvm/ioreq.h
> @@ -0,0 +1,72 @@
> +/*
> + * hvm.h: Hardware virtual machine assist interface definitions.
> + *
> + * Copyright (c) 2016 Citrix Systems Inc.
> + * Copyright (c) 2019 Arm ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along
> with
> + * this program; If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#ifndef __ASM_ARM_HVM_IOREQ_H__
> +#define __ASM_ARM_HVM_IOREQ_H__
> +
> +#ifdef CONFIG_IOREQ_SERVER
> +enum io_state handle_ioserv(struct cpu_user_regs *regs, struct vcpu *v);
> +enum io_state try_fwd_ioserv(struct cpu_user_regs *regs,
> + struct vcpu *v, mmio_info_t *info);
> +#else
> +static inline enum io_state handle_ioserv(struct cpu_user_regs *regs,
> + struct vcpu *v)
> +{
> + return IO_UNHANDLED;
> +}
> +
> +static inline enum io_state try_fwd_ioserv(struct cpu_user_regs *regs,
> + struct vcpu *v, mmio_info_t *info)
> +{
> + return IO_UNHANDLED;
> +}
> +#endif
> +
> +bool ioreq_complete_mmio(void);
> +
> +static inline bool handle_pio(uint16_t port, unsigned int size, int dir)
> +{
> + /*
> + * TODO: For Arm64, the main user will be PCI. So this should be
> + * implemented when we add support for vPCI.
> + */
> + ASSERT_UNREACHABLE();
> + return true;
> +}
> +
> +static inline void msix_write_completion(struct vcpu *v)
> +{
> +}
> +
> +/* This correlation must not be altered */
> +#define IOREQ_STATUS_HANDLED IO_HANDLED
> +#define IOREQ_STATUS_UNHANDLED IO_UNHANDLED
> +#define IOREQ_STATUS_RETRY IO_RETRY
> +
> +#endif /* __ASM_ARM_HVM_IOREQ_H__ */
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * tab-width: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/xen/include/asm-arm/mmio.h b/xen/include/asm-arm/mmio.h
> index 8dbfb27..7ab873c 100644
> --- a/xen/include/asm-arm/mmio.h
> +++ b/xen/include/asm-arm/mmio.h
> @@ -37,6 +37,7 @@ enum io_state
> IO_ABORT, /* The IO was handled by the helper and led to an abort.
> */
> IO_HANDLED, /* The IO was successfully handled by the helper. */
> IO_UNHANDLED, /* The IO was not handled by the helper. */
> + IO_RETRY, /* Retry the emulation for some reason */
> };
>
> typedef int (*mmio_read_t)(struct vcpu *v, mmio_info_t *info,
> --
> 2.7.4
>
