Return to xen_bus_dma.c CVS log

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Modifications for the Xen suspend/migrate/resume branch:

- introduce xenbus_device_{suspend,resume}() functions. These are routines
used to suspend/resume MI parts of the Xenbus device interfaces, like updating
frontend/backend devices' paths found in XenStore.

- introduce HYPERVISOR_sysctl(), an hypercall used only by Xentools to obtain
information from hypervisor (listing VMs, printing console, etc.). I use it
to query xenconsole from ddb(), as a last resort in case of a panic() in
dom0 (xm being not available). Currently unused in the branch; could be, if
requested.

- disable the rwlock(9) used to protect code that could use transient MFNs.
It could trigger nasty context switches in place it should not to.

- fix some bugs in the xennet/xbd suspend/resume pmf(9) handlers.

- following XenSource's design, talk_to_otherend() is now called
watch_otherend(), and free_otherend_details() is used by Xenbus device
suspend/resume routines.

- some slight modifications in pmap regarding APDP. Introduce an inline
function (pmap_unmap_apdp_pde()) that clears APDP entry for the current pmap.

- similarly, implement pmap_unmap_all_apdp_pdes() that iterates through all
pmaps and tears down APDP, as Xen does not handle them properly.

TODO/XXX:

- pmap_unmap_apdp_pde() does not handle APDP shadow entry of PAE. It will,
once I figure out how PAE uses it.

- revisit the pmap locking issue regarding transient MFNs. As NetBSD does not
use kernel preemption and MP for Xen, this could be skipped momentarily. See
http://mail-index.netbsd.org/port-xen/2009/04/27/msg004903.html for details.

- fix a bug regarding grant tables which could technically DoS a dom0 if
ridiculously high consumer/producer indexes are passed down in the ring during
a resume.

All in all, once the grant table index issue and APDP PAE are fixed, next step
is to torture test this branch.

Tested under i386 PAE and non-PAE, Xen3 dom0 and domU. amd64 is only compile
tested.

/*	$NetBSD: xen_bus_dma.c,v 1.14.2.2 2009/05/31 20:15:37 jym Exp $	*/
/*	NetBSD bus_dma.c,v 1.21 2005/04/16 07:53:35 yamt Exp */

/*-
 * Copyright (c) 1996, 1997, 1998 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Charles M. Hannum and by Jason R. Thorpe of the Numerical Aerospace
 * Simulation Facility, NASA Ames Research Center.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: xen_bus_dma.c,v 1.14.2.2 2009/05/31 20:15:37 jym Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/mbuf.h>
#include <sys/proc.h>

#include <machine/bus.h>
#include <machine/bus_private.h>

#include <uvm/uvm_extern.h>

extern paddr_t avail_end;

/* Pure 2^n version of get_order */
static inline int get_order(unsigned long size)
{
	int order = -1;
	size = (size - 1) >> (PAGE_SHIFT - 1);
	do {
		size >>= 1;
		order++;
	} while (size);
	return order;
}

static int
_xen_alloc_contig(bus_size_t size, bus_size_t alignment, bus_size_t boundary,
    struct pglist *mlistp, int flags, bus_addr_t low, bus_addr_t high)
{
	int order, i;
	unsigned long npagesreq, npages, mfn;
	bus_addr_t pa;
	struct vm_page *pg, *pgnext;
	int s, error;
#ifdef XEN3
	struct xen_memory_reservation res;
#endif

	/*
	 * When requesting a contigous memory region, the hypervisor will
	 * return a memory range aligned on size. This will automagically
	 * handle "boundary", but the only way to enforce alignment
	 * is to request a memory region of size max(alignment, size).
	 */
	order = max(get_order(size), get_order(alignment));
	npages = (1 << order);
	npagesreq = (size >> PAGE_SHIFT);
	KASSERT(npages >= npagesreq);

	/* get npages from UWM, and give them back to the hypervisor */
	error = uvm_pglistalloc(npages << PAGE_SHIFT, 0, avail_end, 0, 0,
	    mlistp, npages, (flags & BUS_DMA_NOWAIT) == 0);
	if (error)
		return (error);

	xen_acquire_reader_ptom_lock();
	for (pg = mlistp->tqh_first; pg != NULL; pg = pg->pageq.queue.tqe_next) {
		pa = VM_PAGE_TO_PHYS(pg);
		mfn = xpmap_ptom(pa) >> PAGE_SHIFT;
		xpmap_phys_to_machine_mapping[
		    (pa - XPMAP_OFFSET) >> PAGE_SHIFT] = INVALID_P2M_ENTRY;
#ifdef XEN3
		xenguest_handle(res.extent_start) = &mfn;
		res.nr_extents = 1;
		res.extent_order = 0;
		res.domid = DOMID_SELF;
		if (HYPERVISOR_memory_op(XENMEM_decrease_reservation, &res)
		    != 1) {
#ifdef DEBUG
			printf("xen_alloc_contig: XENMEM_decrease_reservation "
			    "failed!\n");
#endif
			xpmap_phys_to_machine_mapping[
			    (pa - XPMAP_OFFSET) >> PAGE_SHIFT] = mfn;

			error = ENOMEM;
			goto failed;
		}
#else
		if (HYPERVISOR_dom_mem_op(MEMOP_decrease_reservation,
		    &mfn, 1, 0) != 1) {
#ifdef DEBUG
			printf("xen_alloc_contig: MEMOP_decrease_reservation "
			    "failed!\n");
#endif
			xpmap_phys_to_machine_mapping[
			    (pa - XPMAP_OFFSET) >> PAGE_SHIFT] = mfn;
			error = ENOMEM;
			goto failed;
		}
#endif
	}

	/* Get the new contiguous memory extent */
#ifdef XEN3
	xenguest_handle(res.extent_start) = &mfn;
	res.nr_extents = 1;
	res.extent_order = order;
	res.address_bits = get_order(high) + PAGE_SHIFT;
	res.domid = DOMID_SELF;
	error = HYPERVISOR_memory_op(XENMEM_increase_reservation, &res);
	if (error != 1) {
#ifdef DEBUG
		printf("xen_alloc_contig: XENMEM_increase_reservation "
		    "failed: %d (order %d address_bits %d)\n",
		    error, order, res.address_bits);
#endif
		error = ENOMEM;
		pg = NULL;
		goto failed;
	}
#else
	if (HYPERVISOR_dom_mem_op(MEMOP_increase_reservation,
	    &mfn, 1, order) != 1) {
#ifdef DEBUG
		printf("xen_alloc_contig: MEMOP_increase_reservation "
		    "failed!\n");
#endif
		error = ENOMEM;
		pg = NULL;
		goto failed;
	}
#endif
	s = splvm();
	/* Map the new extent in place of the old pages */
	for (pg = mlistp->tqh_first, i = 0; pg != NULL; pg = pgnext, i++) {
		pgnext = pg->pageq.queue.tqe_next;
		pa = VM_PAGE_TO_PHYS(pg);
		xpmap_phys_to_machine_mapping[
		    (pa - XPMAP_OFFSET) >> PAGE_SHIFT] = mfn+i;
		xpq_queue_machphys_update((mfn+i) << PAGE_SHIFT, pa);
		/* while here, give extra pages back to UVM */
		if (i >= npagesreq) {
			TAILQ_REMOVE(mlistp, pg, pageq.queue);
			uvm_pagefree(pg);
		}
	}

	/* Flush updates through and flush the TLB */
	xpq_queue_tlb_flush();
	xpq_flush_queue();
	splx(s);

	xen_release_ptom_lock();
	return 0;

failed:
	/*
	 * Attempt to recover from a failed decrease or increase reservation:
	 * if decrease_reservation failed, we don't have given all pages
	 * back to Xen; give them back to UVM, and get the missing pages
	 * from Xen.
	 * if increase_reservation failed, we expect pg to be NULL and we just
	 * get back the missing pages from Xen one by one.
	 */
	/* give back remaining pages to UVM */
	for (; pg != NULL; pg = pgnext) {
		pgnext = pg->pageq.queue.tqe_next;
		TAILQ_REMOVE(mlistp, pg, pageq.queue);
		uvm_pagefree(pg);
	}
	/* remplace the pages that we already gave to Xen */
	s = splvm();
	for (pg = mlistp->tqh_first; pg != NULL; pg = pgnext) {
		pgnext = pg->pageq.queue.tqe_next;
#ifdef XEN3
		xenguest_handle(res.extent_start) = &mfn;
		res.nr_extents = 1;
		res.extent_order = 0;
		res.address_bits = 32;
		res.domid = DOMID_SELF;
		if (HYPERVISOR_memory_op(XENMEM_increase_reservation, &res)
		    < 0) {
			printf("xen_alloc_contig: recovery "
			    "XENMEM_increase_reservation failed!\n");
			break;
		}
#else
		if (HYPERVISOR_dom_mem_op(MEMOP_increase_reservation,
		    &mfn, 1, 0) != 1) {
			printf("xen_alloc_contig: recovery "
			    "MEMOP_increase_reservation failed!\n");
			break;
		}
#endif
		pa = VM_PAGE_TO_PHYS(pg);
		xpmap_phys_to_machine_mapping[
		    (pa - XPMAP_OFFSET) >> PAGE_SHIFT] = mfn;
		xpq_queue_machphys_update((mfn) << PAGE_SHIFT, pa);
		TAILQ_REMOVE(mlistp, pg, pageq.queue);
		uvm_pagefree(pg);
	}
	/* Flush updates through and flush the TLB */
	xpq_queue_tlb_flush();
	xpq_flush_queue();
	splx(s);
	return error;
}


/*
 * Allocate physical memory from the given physical address range.
 * Called by DMA-safe memory allocation methods.
 * We need our own version to deal with physical vs machine addresses.
 */
int
_xen_bus_dmamem_alloc_range(bus_dma_tag_t t, bus_size_t size,
    bus_size_t alignment, bus_size_t boundary, bus_dma_segment_t *segs,
    int nsegs, int *rsegs, int flags, bus_addr_t low, bus_addr_t high)
{
	bus_addr_t curaddr, lastaddr;
	struct vm_page *m;
	struct pglist mlist;
	int curseg, error;
	int doingrealloc = 0;

	/* Always round the size. */
	size = round_page(size);

	KASSERT((alignment & (alignment - 1)) == 0);
	KASSERT((boundary & (boundary - 1)) == 0);
	if (alignment < PAGE_SIZE)
		alignment = PAGE_SIZE;
	if (boundary != 0 && boundary < size)
		return (EINVAL);

	/*
	 * Allocate pages from the VM system.
	 */
	error = uvm_pglistalloc(size, 0, avail_end, alignment, boundary,
	    &mlist, nsegs, (flags & BUS_DMA_NOWAIT) == 0);
	if (error)
		return (error);

	xen_acquire_reader_ptom_lock();

again:

	/*
	 * Compute the location, size, and number of segments actually
	 * returned by the VM code.
	 */
	m = mlist.tqh_first;
	curseg = 0;
	curaddr = lastaddr = segs[curseg].ds_addr = _BUS_VM_PAGE_TO_BUS(m);
	if (curaddr < low || curaddr >= high)
		goto badaddr;
	segs[curseg].ds_len = PAGE_SIZE;
	m = m->pageq.queue.tqe_next;
	if ((segs[curseg].ds_addr & (alignment - 1)) != 0)
		goto dorealloc;

	for (; m != NULL; m = m->pageq.queue.tqe_next) {
		curaddr = _BUS_VM_PAGE_TO_BUS(m);
		if (curaddr < low || curaddr >= high)
			goto badaddr;
		if (curaddr == (lastaddr + PAGE_SIZE)) {
			segs[curseg].ds_len += PAGE_SIZE;
			if ((lastaddr & boundary) != (curaddr & boundary))
				goto dorealloc;
		} else {
			curseg++;
			if (curseg >= nsegs || (curaddr & (alignment - 1)) != 0)
				goto dorealloc;
			segs[curseg].ds_addr = curaddr;
			segs[curseg].ds_len = PAGE_SIZE;
		}
		lastaddr = curaddr;
	}

	*rsegs = curseg + 1;
	xen_release_ptom_lock();
	return (0);

badaddr:
#ifdef XEN3
	if (doingrealloc == 0)
		goto dorealloc;
	if (curaddr < low) {
		/* no way to enforce this */
		printf("_xen_bus_dmamem_alloc_range: no way to "
		    "enforce address range (0x%" PRIx64 " - 0x%" PRIx64 ")\n",
		    (uint64_t)low, (uint64_t)high);
		uvm_pglistfree(&mlist);
		xen_release_ptom_lock();
		return EINVAL;
	}
	printf("xen_bus_dmamem_alloc_range: "
	    "curraddr=0x%lx > high=0x%lx\n",
	    (u_long)curaddr, (u_long)high);
	panic("xen_bus_dmamem_alloc_range 1");
#else /* !XEN3 */
	/*
	 * If machine addresses are outside the allowed
	 * range we have to bail. Xen2 doesn't offer an
	 * interface to get memory in a specific address
	 * range.
	 */
	printf("_xen_bus_dmamem_alloc_range: no way to "
	    "enforce address range\n");
	uvm_pglistfree(&mlist);
	xen_release_ptom_lock();
	return EINVAL;
#endif /* XEN3 */
dorealloc:
	if (doingrealloc == 1)
		panic("_xen_bus_dmamem_alloc_range: "
		   "xen_alloc_contig returned "
		   "too much segments");
	doingrealloc = 1;
	/*
	 * Too much segments, or memory doesn't fit
	 * constraints. Free this memory and
	 * get a contigous segment from the hypervisor.
	 */
	uvm_pglistfree(&mlist);
	for (curseg = 0; curseg < nsegs; curseg++) {
		segs[curseg].ds_addr = 0;
		segs[curseg].ds_len = 0;
	}
	error = _xen_alloc_contig(size, alignment,
	    boundary, &mlist, flags, low, high);
	if (error) {
		xen_release_ptom_lock();
		return error;
	}
	goto again;
}