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Date: Fri, 28 Mar 2008 13:09:48 -0700
From: Jeremy Fitzhardinge <jeremy@...p.org>
To: Isaku Yamahata <yamahata@...inux.co.jp>
CC: chrisw@...s-sol.org, sct@...hat.com,
virtualization@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, xen-ia64-devel@...ts.xensource.com,
eddie.dong@...el.com
Subject: Re: [PATCH 12/12] xen: import arch generic part of xencomm.
Isaku Yamahata wrote:
> On xen/ia64 and xen/powerpc hypercall arguments are passed by pseudo
> physical address (guest physical address) so that it's necessary to
> convert from virtual address into pseudo physical address. The frame
> work is called xencomm.
> Import arch generic part of xencomm.
>
> Signed-off-by: Isaku Yamahata <yamahata@...inux.co.jp>
> ---
> drivers/xen/Makefile | 1 +
> drivers/xen/xencomm.c | 232 +++++++++++++++++++++++++++++++++++++++
> include/xen/interface/xencomm.h | 41 +++++++
> include/xen/xencomm.h | 77 +++++++++++++
>
There's no Kconfig for this.
What ends up using xencomm? Could we defer adding it until there's an
in-tree user?
J
> 4 files changed, 351 insertions(+), 0 deletions(-)
> create mode 100644 drivers/xen/xencomm.c
> create mode 100644 include/xen/interface/xencomm.h
> create mode 100644 include/xen/xencomm.h
>
> diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
> index 823ce78..43f014c 100644
> --- a/drivers/xen/Makefile
> +++ b/drivers/xen/Makefile
> @@ -1,2 +1,3 @@
> obj-y += grant-table.o features.o events.o
> obj-y += xenbus/
> +obj-$(CONFIG_XEN_XENCOMM) += xencomm.o
> diff --git a/drivers/xen/xencomm.c b/drivers/xen/xencomm.c
> new file mode 100644
> index 0000000..797cb4e
> --- /dev/null
> +++ b/drivers/xen/xencomm.c
> @@ -0,0 +1,232 @@
> +/*
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that 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, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
> + *
> + * Copyright (C) IBM Corp. 2006
> + *
> + * Authors: Hollis Blanchard <hollisb@...ibm.com>
> + */
> +
> +#include <linux/gfp.h>
> +#include <linux/mm.h>
> +#include <asm/page.h>
> +#include <xen/xencomm.h>
> +#include <xen/interface/xen.h>
> +#ifdef __ia64__
> +#include <asm/xen/xencomm.h> /* for is_kern_addr() */
> +#endif
> +
> +#ifdef HAVE_XEN_PLATFORM_COMPAT_H
> +#include <xen/platform-compat.h>
> +#endif
> +
> +static int xencomm_init(struct xencomm_desc *desc,
> + void *buffer, unsigned long bytes)
> +{
> + unsigned long recorded = 0;
> + int i = 0;
> +
> + while ((recorded < bytes) && (i < desc->nr_addrs)) {
> + unsigned long vaddr = (unsigned long)buffer + recorded;
> + unsigned long paddr;
> + int offset;
> + int chunksz;
> +
> + offset = vaddr % PAGE_SIZE; /* handle partial pages */
> + chunksz = min(PAGE_SIZE - offset, bytes - recorded);
> +
> + paddr = xencomm_vtop(vaddr);
> + if (paddr == ~0UL) {
> + printk(KERN_DEBUG "%s: couldn't translate vaddr %lx\n",
> + __func__, vaddr);
> + return -EINVAL;
> + }
> +
> + desc->address[i++] = paddr;
> + recorded += chunksz;
> + }
> +
> + if (recorded < bytes) {
> + printk(KERN_DEBUG
> + "%s: could only translate %ld of %ld bytes\n",
> + __func__, recorded, bytes);
> + return -ENOSPC;
> + }
> +
> + /* mark remaining addresses invalid (just for safety) */
> + while (i < desc->nr_addrs)
> + desc->address[i++] = XENCOMM_INVALID;
> +
> + desc->magic = XENCOMM_MAGIC;
> +
> + return 0;
> +}
> +
> +static struct xencomm_desc *xencomm_alloc(gfp_t gfp_mask,
> + void *buffer, unsigned long bytes)
> +{
> + struct xencomm_desc *desc;
> + unsigned long buffer_ulong = (unsigned long)buffer;
> + unsigned long start = buffer_ulong & PAGE_MASK;
> + unsigned long end = (buffer_ulong + bytes) | ~PAGE_MASK;
> + unsigned long nr_addrs = (end - start + 1) >> PAGE_SHIFT;
> + unsigned long size = sizeof(*desc) +
> + sizeof(desc->address[0]) * nr_addrs;
> +
> + /*
> + * slab allocator returns at least sizeof(void*) aligned pointer.
> + * When sizeof(*desc) > sizeof(void*), struct xencomm_desc might
> + * cross page boundary.
> + */
> + if (sizeof(*desc) > sizeof(void *)) {
> + unsigned long order = get_order(size);
> + desc = (struct xencomm_desc *)__get_free_pages(gfp_mask,
> + order);
> + if (desc == NULL)
> + return NULL;
> +
> + desc->nr_addrs =
> + ((PAGE_SIZE << order) - sizeof(struct xencomm_desc)) /
> + sizeof(*desc->address);
> + } else {
> + desc = kmalloc(size, gfp_mask);
> + if (desc == NULL)
> + return NULL;
> +
> + desc->nr_addrs = nr_addrs;
> + }
> + return desc;
> +}
> +
> +void xencomm_free(struct xencomm_handle *desc)
> +{
> + if (desc && !((ulong)desc & XENCOMM_INLINE_FLAG)) {
> + struct xencomm_desc *desc__ = (struct xencomm_desc *)desc;
> + if (sizeof(*desc__) > sizeof(void *)) {
> + unsigned long size = sizeof(*desc__) +
> + sizeof(desc__->address[0]) * desc__->nr_addrs;
> + unsigned long order = get_order(size);
> + free_pages((unsigned long)__va(desc), order);
> + } else
> + kfree(__va(desc));
> + }
> +}
> +
> +static int xencomm_create(void *buffer, unsigned long bytes,
> + struct xencomm_desc **ret, gfp_t gfp_mask)
> +{
> + struct xencomm_desc *desc;
> + int rc;
> +
> + pr_debug("%s: %p[%ld]\n", __func__, buffer, bytes);
> +
> + if (bytes == 0) {
> + /* don't create a descriptor; Xen recognizes NULL. */
> + BUG_ON(buffer != NULL);
> + *ret = NULL;
> + return 0;
> + }
> +
> + BUG_ON(buffer == NULL); /* 'bytes' is non-zero */
> +
> + desc = xencomm_alloc(gfp_mask, buffer, bytes);
> + if (!desc) {
> + printk(KERN_DEBUG "%s failure\n", "xencomm_alloc");
> + return -ENOMEM;
> + }
> +
> + rc = xencomm_init(desc, buffer, bytes);
> + if (rc) {
> + printk(KERN_DEBUG "%s failure: %d\n", "xencomm_init", rc);
> + xencomm_free((struct xencomm_handle *)__pa(desc));
> + return rc;
> + }
> +
> + *ret = desc;
> + return 0;
> +}
> +
> +/* check if memory address is within VMALLOC region */
> +static int is_phys_contiguous(unsigned long addr)
> +{
> + if (!is_kernel_addr(addr))
> + return 0;
> +
> + return (addr < VMALLOC_START) || (addr >= VMALLOC_END);
> +}
> +
> +static struct xencomm_handle *xencomm_create_inline(void *ptr)
> +{
> + unsigned long paddr;
> +
> + BUG_ON(!is_phys_contiguous((unsigned long)ptr));
> +
> + paddr = (unsigned long)xencomm_pa(ptr);
> + BUG_ON(paddr & XENCOMM_INLINE_FLAG);
> + return (struct xencomm_handle *)(paddr | XENCOMM_INLINE_FLAG);
> +}
> +
> +/* "mini" routine, for stack-based communications: */
> +static int xencomm_create_mini(void *buffer,
> + unsigned long bytes, struct xencomm_mini *xc_desc,
> + struct xencomm_desc **ret)
> +{
> + int rc = 0;
> + struct xencomm_desc *desc;
> + BUG_ON(((unsigned long)xc_desc) % sizeof(*xc_desc) != 0);
> +
> + desc = (void *)xc_desc;
> +
> + desc->nr_addrs = XENCOMM_MINI_ADDRS;
> +
> + rc = xencomm_init(desc, buffer, bytes);
> + if (!rc)
> + *ret = desc;
> +
> + return rc;
> +}
> +
> +struct xencomm_handle *xencomm_map(void *ptr, unsigned long bytes)
> +{
> + int rc;
> + struct xencomm_desc *desc;
> +
> + if (is_phys_contiguous((unsigned long)ptr))
> + return xencomm_create_inline(ptr);
> +
> + rc = xencomm_create(ptr, bytes, &desc, GFP_KERNEL);
> +
> + if (rc || desc == NULL)
> + return NULL;
> +
> + return xencomm_pa(desc);
> +}
> +
> +struct xencomm_handle *__xencomm_map_no_alloc(void *ptr, unsigned long bytes,
> + struct xencomm_mini *xc_desc)
> +{
> + int rc;
> + struct xencomm_desc *desc = NULL;
> +
> + if (is_phys_contiguous((unsigned long)ptr))
> + return xencomm_create_inline(ptr);
> +
> + rc = xencomm_create_mini(ptr, bytes, xc_desc,
> + &desc);
> +
> + if (rc)
> + return NULL;
> +
> + return xencomm_pa(desc);
> +}
> diff --git a/include/xen/interface/xencomm.h b/include/xen/interface/xencomm.h
> new file mode 100644
> index 0000000..ac45e07
> --- /dev/null
> +++ b/include/xen/interface/xencomm.h
> @@ -0,0 +1,41 @@
> +/*
> + * 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) IBM Corp. 2006
> + */
> +
> +#ifndef _XEN_XENCOMM_H_
> +#define _XEN_XENCOMM_H_
> +
> +/* A xencomm descriptor is a scatter/gather list containing physical
> + * addresses corresponding to a virtually contiguous memory area. The
> + * hypervisor translates these physical addresses to machine addresses to copy
> + * to and from the virtually contiguous area.
> + */
> +
> +#define XENCOMM_MAGIC 0x58434F4D /* 'XCOM' */
> +#define XENCOMM_INVALID (~0UL)
> +
> +struct xencomm_desc {
> + uint32_t magic;
> + uint32_t nr_addrs; /* the number of entries in address[] */
> + uint64_t address[0];
> +};
> +
> +#endif /* _XEN_XENCOMM_H_ */
> diff --git a/include/xen/xencomm.h b/include/xen/xencomm.h
> new file mode 100644
> index 0000000..e43b039
> --- /dev/null
> +++ b/include/xen/xencomm.h
> @@ -0,0 +1,77 @@
> +/*
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that 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, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
> + *
> + * Copyright (C) IBM Corp. 2006
> + *
> + * Authors: Hollis Blanchard <hollisb@...ibm.com>
> + * Jerone Young <jyoung5@...ibm.com>
> + */
> +
> +#ifndef _LINUX_XENCOMM_H_
> +#define _LINUX_XENCOMM_H_
> +
> +#include <xen/interface/xencomm.h>
> +
> +#define XENCOMM_MINI_ADDRS 3
> +struct xencomm_mini {
> + struct xencomm_desc _desc;
> + uint64_t address[XENCOMM_MINI_ADDRS];
> +};
> +
> +/* To avoid additionnal virt to phys conversion, an opaque structure is
> + presented. */
> +struct xencomm_handle;
> +
> +extern void xencomm_free(struct xencomm_handle *desc);
> +extern struct xencomm_handle *xencomm_map(void *ptr, unsigned long bytes);
> +extern struct xencomm_handle *__xencomm_map_no_alloc(void *ptr,
> + unsigned long bytes, struct xencomm_mini *xc_area);
> +
> +#if 0
> +#define XENCOMM_MINI_ALIGNED(xc_desc, n) \
> + struct xencomm_mini xc_desc ## _base[(n)] \
> + __attribute__((__aligned__(sizeof(struct xencomm_mini)))); \
> + struct xencomm_mini *xc_desc = &xc_desc ## _base[0];
> +#else
> +/*
> + * gcc bug workaround:
> + * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16660
> + * gcc doesn't handle properly stack variable with
> + * __attribute__((__align__(sizeof(struct xencomm_mini))))
> + */
> +#define XENCOMM_MINI_ALIGNED(xc_desc, n) \
> + unsigned char xc_desc ## _base[((n) + 1 ) * \
> + sizeof(struct xencomm_mini)]; \
> + struct xencomm_mini *xc_desc = (struct xencomm_mini *) \
> + ((unsigned long)xc_desc ## _base + \
> + (sizeof(struct xencomm_mini) - \
> + ((unsigned long)xc_desc ## _base) % \
> + sizeof(struct xencomm_mini)));
> +#endif
> +#define xencomm_map_no_alloc(ptr, bytes) \
> + ({ XENCOMM_MINI_ALIGNED(xc_desc, 1); \
> + __xencomm_map_no_alloc(ptr, bytes, xc_desc); })
> +
> +/* provided by architecture code: */
> +extern unsigned long xencomm_vtop(unsigned long vaddr);
> +
> +static inline void *xencomm_pa(void *ptr)
> +{
> + return (void *)xencomm_vtop((unsigned long)ptr);
> +}
> +
> +#define xen_guest_handle(hnd) ((hnd).p)
> +
> +#endif /* _LINUX_XENCOMM_H_ */
>
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