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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen master] x86/mem-paging: move code to its dedicated source file
commit 02a2b19c8e2532998e262727d32c574267ac6b48
Author: Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Mon May 18 17:16:55 2020 +0200
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon May 18 17:16:55 2020 +0200
x86/mem-paging: move code to its dedicated source file
Do a little bit of style adjustment along the way, and drop the
"p2m_mem_paging_" prefixes from the now static functions.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
xen/arch/x86/mm/mem_paging.c | 417 ++++++++++++++++++++++++++++++++++++++++++-
xen/arch/x86/mm/p2m.c | 409 ------------------------------------------
xen/include/asm-x86/p2m.h | 7 -
3 files changed, 414 insertions(+), 419 deletions(-)
diff --git a/xen/arch/x86/mm/mem_paging.c b/xen/arch/x86/mm/mem_paging.c
index 54a94fa3a0..84b05cd461 100644
--- a/xen/arch/x86/mm/mem_paging.c
+++ b/xen/arch/x86/mm/mem_paging.c
@@ -25,6 +25,417 @@
#include <xen/vm_event.h>
#include <xsm/xsm.h>
+#include "mm-locks.h"
+
+/*
+ * p2m_mem_paging_drop_page - Tell pager to drop its reference to a paged page
+ * @d: guest domain
+ * @gfn: guest page to drop
+ *
+ * p2m_mem_paging_drop_page() will notify the pager that a paged-out gfn was
+ * released by the guest. The pager is supposed to drop its reference of the
+ * gfn.
+ */
+void p2m_mem_paging_drop_page(struct domain *d, unsigned long gfn,
+ p2m_type_t p2mt)
+{
+ vm_event_request_t req = {
+ .reason = VM_EVENT_REASON_MEM_PAGING,
+ .u.mem_paging.gfn = gfn
+ };
+
+ /*
+ * We allow no ring in this unique case, because it won't affect
+ * correctness of the guest execution at this point. If this is the only
+ * page that happens to be paged-out, we'll be okay.. but it's likely the
+ * guest will crash shortly anyways.
+ */
+ int rc = vm_event_claim_slot(d, d->vm_event_paging);
+
+ if ( rc < 0 )
+ return;
+
+ /* Send release notification to pager */
+ req.u.mem_paging.flags = MEM_PAGING_DROP_PAGE;
+
+ /* Update stats unless the page hasn't yet been evicted */
+ if ( p2mt != p2m_ram_paging_out )
+ atomic_dec(&d->paged_pages);
+ else
+ /* Evict will fail now, tag this request for pager */
+ req.u.mem_paging.flags |= MEM_PAGING_EVICT_FAIL;
+
+ vm_event_put_request(d, d->vm_event_paging, &req);
+}
+
+/*
+ * p2m_mem_paging_populate - Tell pager to populate a paged page
+ * @d: guest domain
+ * @gfn: guest page in paging state
+ *
+ * p2m_mem_paging_populate() will notify the pager that a page in any of the
+ * paging states needs to be written back into the guest.
+ * This function needs to be called whenever gfn_to_mfn() returns any of the
p2m
+ * paging types because the gfn may not be backed by a mfn.
+ *
+ * The gfn can be in any of the paging states, but the pager needs only be
+ * notified when the gfn is in the paging-out path (paging_out or paged). This
+ * function may be called more than once from several vcpus. If the vcpu
belongs
+ * to the guest, the vcpu must be stopped and the pager notified that the vcpu
+ * was stopped. The pager needs to handle several requests for the same gfn.
+ *
+ * If the gfn is not in the paging-out path and the vcpu does not belong to the
+ * guest, nothing needs to be done and the function assumes that a request was
+ * already sent to the pager. In this case the caller has to try again until
the
+ * gfn is fully paged in again.
+ */
+void p2m_mem_paging_populate(struct domain *d, unsigned long gfn_l)
+{
+ struct vcpu *v = current;
+ vm_event_request_t req = {
+ .reason = VM_EVENT_REASON_MEM_PAGING,
+ .u.mem_paging.gfn = gfn_l
+ };
+ p2m_type_t p2mt;
+ p2m_access_t a;
+ gfn_t gfn = _gfn(gfn_l);
+ mfn_t mfn;
+ struct p2m_domain *p2m = p2m_get_hostp2m(d);
+ int rc = vm_event_claim_slot(d, d->vm_event_paging);
+
+ /* We're paging. There should be a ring. */
+ if ( rc == -EOPNOTSUPP )
+ {
+ gdprintk(XENLOG_ERR, "Dom%d paging gfn %lx yet no ring in place\n",
+ d->domain_id, gfn_l);
+ /* Prevent the vcpu from faulting repeatedly on the same gfn */
+ if ( v->domain == d )
+ vcpu_pause_nosync(v);
+ domain_crash(d);
+ return;
+ }
+ else if ( rc < 0 )
+ return;
+
+ /* Fix p2m mapping */
+ gfn_lock(p2m, gfn, 0);
+ mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, 0, NULL, NULL);
+ /* Allow only nominated or evicted pages to enter page-in path */
+ if ( p2mt == p2m_ram_paging_out || p2mt == p2m_ram_paged )
+ {
+ /* Evict will fail now, tag this request for pager */
+ if ( p2mt == p2m_ram_paging_out )
+ req.u.mem_paging.flags |= MEM_PAGING_EVICT_FAIL;
+
+ rc = p2m_set_entry(p2m, gfn, mfn, PAGE_ORDER_4K, p2m_ram_paging_in, a);
+ }
+ gfn_unlock(p2m, gfn, 0);
+ if ( rc < 0 )
+ goto out_cancel;
+
+ /* Pause domain if request came from guest and gfn has paging type */
+ if ( p2m_is_paging(p2mt) && v->domain == d )
+ {
+ vm_event_vcpu_pause(v);
+ req.flags |= VM_EVENT_FLAG_VCPU_PAUSED;
+ }
+ /* No need to inform pager if the gfn is not in the page-out path */
+ else if ( p2mt != p2m_ram_paging_out && p2mt != p2m_ram_paged )
+ {
+ /* gfn is already on its way back and vcpu is not paused */
+ out_cancel:
+ vm_event_cancel_slot(d, d->vm_event_paging);
+ return;
+ }
+
+ /* Send request to pager */
+ req.u.mem_paging.p2mt = p2mt;
+ req.vcpu_id = v->vcpu_id;
+
+ vm_event_put_request(d, d->vm_event_paging, &req);
+}
+
+/*
+ * p2m_mem_paging_resume - Resume guest gfn
+ * @d: guest domain
+ * @rsp: vm_event response received
+ *
+ * p2m_mem_paging_resume() will forward the p2mt of a gfn to ram_rw. It is
+ * called by the pager.
+ *
+ * The gfn was previously either evicted and populated, or nominated and
+ * populated. If the page was evicted the p2mt will be p2m_ram_paging_in. If
+ * the page was just nominated the p2mt will be p2m_ram_paging_in_start because
+ * the pager did not call prepare().
+ *
+ * If the gfn was dropped the vcpu needs to be unpaused.
+ */
+void p2m_mem_paging_resume(struct domain *d, vm_event_response_t *rsp)
+{
+ struct p2m_domain *p2m = p2m_get_hostp2m(d);
+ p2m_type_t p2mt;
+ p2m_access_t a;
+ mfn_t mfn;
+
+ /* Fix p2m entry if the page was not dropped */
+ if ( !(rsp->u.mem_paging.flags & MEM_PAGING_DROP_PAGE) )
+ {
+ gfn_t gfn = _gfn(rsp->u.mem_access.gfn);
+
+ gfn_lock(p2m, gfn, 0);
+ mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, 0, NULL, NULL);
+ /*
+ * Allow only pages which were prepared properly, or pages which
+ * were nominated but not evicted.
+ */
+ if ( mfn_valid(mfn) && (p2mt == p2m_ram_paging_in) )
+ {
+ int rc = p2m_set_entry(p2m, gfn, mfn, PAGE_ORDER_4K,
+ paging_mode_log_dirty(d) ? p2m_ram_logdirty
+ : p2m_ram_rw, a);
+
+ if ( !rc )
+ set_gpfn_from_mfn(mfn_x(mfn), gfn_x(gfn));
+ }
+ gfn_unlock(p2m, gfn, 0);
+ }
+}
+
+/*
+ * nominate - Mark a guest page as to-be-paged-out
+ * @d: guest domain
+ * @gfn: guest page to nominate
+ *
+ * Returns 0 for success or negative errno values if gfn is not pageable.
+ *
+ * nominate() is called by the pager and checks if a guest page can be paged
+ * out. If the following conditions are met the p2mt will be changed:
+ * - the gfn is backed by a mfn
+ * - the p2mt of the gfn is pageable
+ * - the mfn is not used for IO
+ * - the mfn has exactly one user and has no special meaning
+ *
+ * Once the p2mt is changed the page is readonly for the guest. On success the
+ * pager can write the page contents to disk and later evict the page.
+ */
+static int nominate(struct domain *d, unsigned long gfn_l)
+{
+ struct page_info *page;
+ struct p2m_domain *p2m = p2m_get_hostp2m(d);
+ p2m_type_t p2mt;
+ p2m_access_t a;
+ gfn_t gfn = _gfn(gfn_l);
+ mfn_t mfn;
+ int ret = -EBUSY;
+
+ gfn_lock(p2m, gfn, 0);
+
+ mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, 0, NULL, NULL);
+
+ /* Check if mfn is valid */
+ if ( !mfn_valid(mfn) )
+ goto out;
+
+ /* Check p2m type */
+ if ( !p2m_is_pageable(p2mt) )
+ goto out;
+
+ /* Check for io memory page */
+ if ( is_iomem_page(mfn) )
+ goto out;
+
+ /* Check page count and type */
+ page = mfn_to_page(mfn);
+ if ( (page->count_info & (PGC_count_mask | PGC_allocated)) !=
+ (1 | PGC_allocated) )
+ goto out;
+
+ if ( (page->u.inuse.type_info & PGT_count_mask) != 0 )
+ goto out;
+
+ /* Fix p2m entry */
+ ret = p2m_set_entry(p2m, gfn, mfn, PAGE_ORDER_4K, p2m_ram_paging_out, a);
+
+ out:
+ gfn_unlock(p2m, gfn, 0);
+ return ret;
+}
+
+/*
+ * evict - Mark a guest page as paged-out
+ * @d: guest domain
+ * @gfn: guest page to evict
+ *
+ * Returns 0 for success or negative errno values if eviction is not possible.
+ *
+ * evict() is called by the pager and will free a guest page and release it
+ * back to Xen. If the following conditions are met the page can be freed:
+ * - the gfn is backed by a mfn
+ * - the gfn was nominated
+ * - the mfn has still exactly one user and has no special meaning
+ *
+ * After successful nomination some other process could have mapped the page.
In
+ * this case eviction can not be done. If the gfn was populated before the
pager
+ * could evict it, eviction can not be done either. In this case the gfn is
+ * still backed by a mfn.
+ */
+static int evict(struct domain *d, unsigned long gfn_l)
+{
+ struct page_info *page;
+ p2m_type_t p2mt;
+ p2m_access_t a;
+ gfn_t gfn = _gfn(gfn_l);
+ mfn_t mfn;
+ struct p2m_domain *p2m = p2m_get_hostp2m(d);
+ int ret = -EBUSY;
+
+ gfn_lock(p2m, gfn, 0);
+
+ /* Get mfn */
+ mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, 0, NULL, NULL);
+ if ( unlikely(!mfn_valid(mfn)) )
+ goto out;
+
+ /* Allow only nominated pages */
+ if ( p2mt != p2m_ram_paging_out )
+ goto out;
+
+ /* Get the page so it doesn't get modified under Xen's feet */
+ page = mfn_to_page(mfn);
+ if ( unlikely(!get_page(page, d)) )
+ goto out;
+
+ /* Check page count and type once more */
+ if ( (page->count_info & (PGC_count_mask | PGC_allocated)) !=
+ (2 | PGC_allocated) )
+ goto out_put;
+
+ if ( (page->u.inuse.type_info & PGT_count_mask) != 0 )
+ goto out_put;
+
+ /* Decrement guest domain's ref count of the page */
+ put_page_alloc_ref(page);
+
+ /* Remove mapping from p2m table */
+ ret = p2m_set_entry(p2m, gfn, INVALID_MFN, PAGE_ORDER_4K,
+ p2m_ram_paged, a);
+
+ /* Clear content before returning the page to Xen */
+ scrub_one_page(page);
+
+ /* Track number of paged gfns */
+ atomic_inc(&d->paged_pages);
+
+ out_put:
+ /* Put the page back so it gets freed */
+ put_page(page);
+
+ out:
+ gfn_unlock(p2m, gfn, 0);
+ return ret;
+}
+
+/*
+ * prepare - Allocate a new page for the guest
+ * @d: guest domain
+ * @gfn: guest page in paging state
+ *
+ * prepare() will allocate a new page for the guest if the gfn is not backed
+ * by a mfn. It is called by the pager.
+ * It is required that the gfn was already populated. The gfn may already have
a
+ * mfn if populate was called for gfn which was nominated but not evicted. In
+ * this case only the p2mt needs to be forwarded.
+ */
+static int prepare(struct domain *d, unsigned long gfn_l,
+ XEN_GUEST_HANDLE_64(const_uint8) buffer)
+{
+ struct page_info *page = NULL;
+ p2m_type_t p2mt;
+ p2m_access_t a;
+ gfn_t gfn = _gfn(gfn_l);
+ mfn_t mfn;
+ struct p2m_domain *p2m = p2m_get_hostp2m(d);
+ int ret, page_extant = 1;
+
+ if ( !guest_handle_okay(buffer, PAGE_SIZE) )
+ return -EINVAL;
+
+ gfn_lock(p2m, gfn, 0);
+
+ mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, 0, NULL, NULL);
+
+ ret = -ENOENT;
+ /* Allow missing pages */
+ if ( (p2mt != p2m_ram_paging_in) && (p2mt != p2m_ram_paged) )
+ goto out;
+
+ /* Allocate a page if the gfn does not have one yet */
+ if ( !mfn_valid(mfn) )
+ {
+ void *guest_map;
+
+ /* If the user did not provide a buffer, we disallow */
+ ret = -EINVAL;
+ if ( unlikely(guest_handle_is_null(buffer)) )
+ goto out;
+ /* Get a free page */
+ ret = -ENOMEM;
+ page_alloc_mm_pre_lock(d);
+ page = alloc_domheap_page(d, 0);
+ if ( unlikely(page == NULL) )
+ goto out;
+ if ( unlikely(!get_page(page, d)) )
+ {
+ /*
+ * The domain can't possibly know about this page yet, so failure
+ * here is a clear indication of something fishy going on.
+ */
+ domain_crash(d);
+ page = NULL;
+ goto out;
+ }
+ mfn = page_to_mfn(page);
+ page_extant = 0;
+
+ guest_map = map_domain_page(mfn);
+ ret = copy_from_guest(guest_map, buffer, PAGE_SIZE);
+ unmap_domain_page(guest_map);
+ if ( ret )
+ {
+ ret = -EFAULT;
+ goto out;
+ }
+ }
+
+ /*
+ * Make the page already guest-accessible. If the pager still has a
+ * pending resume operation, it will be idempotent p2m entry-wise, but
+ * will unpause the vcpu.
+ */
+ ret = p2m_set_entry(p2m, gfn, mfn, PAGE_ORDER_4K,
+ paging_mode_log_dirty(d) ? p2m_ram_logdirty
+ : p2m_ram_rw, a);
+ if ( !ret )
+ {
+ set_gpfn_from_mfn(mfn_x(mfn), gfn_l);
+
+ if ( !page_extant )
+ atomic_dec(&d->paged_pages);
+ }
+
+ out:
+ gfn_unlock(p2m, gfn, 0);
+
+ if ( page )
+ {
+ if ( ret )
+ put_page_alloc_ref(page);
+ put_page(page);
+ }
+
+ return ret;
+}
+
int mem_paging_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_paging_op_t) arg)
{
int rc;
@@ -50,15 +461,15 @@ int
mem_paging_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_paging_op_t) arg)
switch( mpo.op )
{
case XENMEM_paging_op_nominate:
- rc = p2m_mem_paging_nominate(d, mpo.gfn);
+ rc = nominate(d, mpo.gfn);
break;
case XENMEM_paging_op_evict:
- rc = p2m_mem_paging_evict(d, mpo.gfn);
+ rc = evict(d, mpo.gfn);
break;
case XENMEM_paging_op_prep:
- rc = p2m_mem_paging_prep(d, mpo.gfn, mpo.buffer);
+ rc = prepare(d, mpo.gfn, mpo.buffer);
if ( !rc )
copyback = 1;
break;
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 59b0b05ed5..cc624281e0 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -23,7 +23,6 @@
* along with this program; If not, see <http://www.gnu.org/licenses/>.
*/
-#include <xen/guest_access.h> /* copy_from_guest() */
#include <xen/iommu.h>
#include <xen/mem_access.h>
#include <xen/vm_event.h>
@@ -1506,414 +1505,6 @@ int set_shared_p2m_entry(struct domain *d, unsigned
long gfn_l, mfn_t mfn)
return rc;
}
-/**
- * p2m_mem_paging_nominate - Mark a guest page as to-be-paged-out
- * @d: guest domain
- * @gfn: guest page to nominate
- *
- * Returns 0 for success or negative errno values if gfn is not pageable.
- *
- * p2m_mem_paging_nominate() is called by the pager and checks if a guest page
- * can be paged out. If the following conditions are met the p2mt will be
- * changed:
- * - the gfn is backed by a mfn
- * - the p2mt of the gfn is pageable
- * - the mfn is not used for IO
- * - the mfn has exactly one user and has no special meaning
- *
- * Once the p2mt is changed the page is readonly for the guest. On success the
- * pager can write the page contents to disk and later evict the page.
- */
-int p2m_mem_paging_nominate(struct domain *d, unsigned long gfn_l)
-{
- struct page_info *page;
- struct p2m_domain *p2m = p2m_get_hostp2m(d);
- p2m_type_t p2mt;
- p2m_access_t a;
- gfn_t gfn = _gfn(gfn_l);
- mfn_t mfn;
- int ret = -EBUSY;
-
- gfn_lock(p2m, gfn, 0);
-
- mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, 0, NULL, NULL);
-
- /* Check if mfn is valid */
- if ( !mfn_valid(mfn) )
- goto out;
-
- /* Check p2m type */
- if ( !p2m_is_pageable(p2mt) )
- goto out;
-
- /* Check for io memory page */
- if ( is_iomem_page(mfn) )
- goto out;
-
- /* Check page count and type */
- page = mfn_to_page(mfn);
- if ( (page->count_info & (PGC_count_mask | PGC_allocated)) !=
- (1 | PGC_allocated) )
- goto out;
-
- if ( (page->u.inuse.type_info & PGT_count_mask) != 0 )
- goto out;
-
- /* Fix p2m entry */
- ret = p2m_set_entry(p2m, gfn, mfn, PAGE_ORDER_4K, p2m_ram_paging_out, a);
-
- out:
- gfn_unlock(p2m, gfn, 0);
- return ret;
-}
-
-/**
- * p2m_mem_paging_evict - Mark a guest page as paged-out
- * @d: guest domain
- * @gfn: guest page to evict
- *
- * Returns 0 for success or negative errno values if eviction is not possible.
- *
- * p2m_mem_paging_evict() is called by the pager and will free a guest page and
- * release it back to Xen. If the following conditions are met the page can be
- * freed:
- * - the gfn is backed by a mfn
- * - the gfn was nominated
- * - the mfn has still exactly one user and has no special meaning
- *
- * After successful nomination some other process could have mapped the page.
In
- * this case eviction can not be done. If the gfn was populated before the
pager
- * could evict it, eviction can not be done either. In this case the gfn is
- * still backed by a mfn.
- */
-int p2m_mem_paging_evict(struct domain *d, unsigned long gfn_l)
-{
- struct page_info *page;
- p2m_type_t p2mt;
- p2m_access_t a;
- gfn_t gfn = _gfn(gfn_l);
- mfn_t mfn;
- struct p2m_domain *p2m = p2m_get_hostp2m(d);
- int ret = -EBUSY;
-
- gfn_lock(p2m, gfn, 0);
-
- /* Get mfn */
- mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, 0, NULL, NULL);
- if ( unlikely(!mfn_valid(mfn)) )
- goto out;
-
- /* Allow only nominated pages */
- if ( p2mt != p2m_ram_paging_out )
- goto out;
-
- /* Get the page so it doesn't get modified under Xen's feet */
- page = mfn_to_page(mfn);
- if ( unlikely(!get_page(page, d)) )
- goto out;
-
- /* Check page count and type once more */
- if ( (page->count_info & (PGC_count_mask | PGC_allocated)) !=
- (2 | PGC_allocated) )
- goto out_put;
-
- if ( (page->u.inuse.type_info & PGT_count_mask) != 0 )
- goto out_put;
-
- /* Decrement guest domain's ref count of the page */
- put_page_alloc_ref(page);
-
- /* Remove mapping from p2m table */
- ret = p2m_set_entry(p2m, gfn, INVALID_MFN, PAGE_ORDER_4K,
- p2m_ram_paged, a);
-
- /* Clear content before returning the page to Xen */
- scrub_one_page(page);
-
- /* Track number of paged gfns */
- atomic_inc(&d->paged_pages);
-
- out_put:
- /* Put the page back so it gets freed */
- put_page(page);
-
- out:
- gfn_unlock(p2m, gfn, 0);
- return ret;
-}
-
-/**
- * p2m_mem_paging_drop_page - Tell pager to drop its reference to a paged page
- * @d: guest domain
- * @gfn: guest page to drop
- *
- * p2m_mem_paging_drop_page() will notify the pager that a paged-out gfn was
- * released by the guest. The pager is supposed to drop its reference of the
- * gfn.
- */
-void p2m_mem_paging_drop_page(struct domain *d, unsigned long gfn,
- p2m_type_t p2mt)
-{
- vm_event_request_t req = {
- .reason = VM_EVENT_REASON_MEM_PAGING,
- .u.mem_paging.gfn = gfn
- };
-
- /* We allow no ring in this unique case, because it won't affect
- * correctness of the guest execution at this point. If this is the only
- * page that happens to be paged-out, we'll be okay.. but it's likely the
- * guest will crash shortly anyways. */
- int rc = vm_event_claim_slot(d, d->vm_event_paging);
- if ( rc < 0 )
- return;
-
- /* Send release notification to pager */
- req.u.mem_paging.flags = MEM_PAGING_DROP_PAGE;
-
- /* Update stats unless the page hasn't yet been evicted */
- if ( p2mt != p2m_ram_paging_out )
- atomic_dec(&d->paged_pages);
- else
- /* Evict will fail now, tag this request for pager */
- req.u.mem_paging.flags |= MEM_PAGING_EVICT_FAIL;
-
- vm_event_put_request(d, d->vm_event_paging, &req);
-}
-
-/**
- * p2m_mem_paging_populate - Tell pager to populate a paged page
- * @d: guest domain
- * @gfn: guest page in paging state
- *
- * p2m_mem_paging_populate() will notify the pager that a page in any of the
- * paging states needs to be written back into the guest.
- * This function needs to be called whenever gfn_to_mfn() returns any of the
p2m
- * paging types because the gfn may not be backed by a mfn.
- *
- * The gfn can be in any of the paging states, but the pager needs only be
- * notified when the gfn is in the paging-out path (paging_out or paged). This
- * function may be called more than once from several vcpus. If the vcpu
belongs
- * to the guest, the vcpu must be stopped and the pager notified that the vcpu
- * was stopped. The pager needs to handle several requests for the same gfn.
- *
- * If the gfn is not in the paging-out path and the vcpu does not belong to the
- * guest, nothing needs to be done and the function assumes that a request was
- * already sent to the pager. In this case the caller has to try again until
the
- * gfn is fully paged in again.
- */
-void p2m_mem_paging_populate(struct domain *d, unsigned long gfn_l)
-{
- struct vcpu *v = current;
- vm_event_request_t req = {
- .reason = VM_EVENT_REASON_MEM_PAGING,
- .u.mem_paging.gfn = gfn_l
- };
- p2m_type_t p2mt;
- p2m_access_t a;
- gfn_t gfn = _gfn(gfn_l);
- mfn_t mfn;
- struct p2m_domain *p2m = p2m_get_hostp2m(d);
-
- /* We're paging. There should be a ring */
- int rc = vm_event_claim_slot(d, d->vm_event_paging);
-
- if ( rc == -EOPNOTSUPP )
- {
- gdprintk(XENLOG_ERR, "Domain %hu paging gfn %lx yet no ring "
- "in place\n", d->domain_id, gfn_l);
- /* Prevent the vcpu from faulting repeatedly on the same gfn */
- if ( v->domain == d )
- vcpu_pause_nosync(v);
- domain_crash(d);
- return;
- }
- else if ( rc < 0 )
- return;
-
- /* Fix p2m mapping */
- gfn_lock(p2m, gfn, 0);
- mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, 0, NULL, NULL);
- /* Allow only nominated or evicted pages to enter page-in path */
- if ( p2mt == p2m_ram_paging_out || p2mt == p2m_ram_paged )
- {
- /* Evict will fail now, tag this request for pager */
- if ( p2mt == p2m_ram_paging_out )
- req.u.mem_paging.flags |= MEM_PAGING_EVICT_FAIL;
-
- rc = p2m_set_entry(p2m, gfn, mfn, PAGE_ORDER_4K, p2m_ram_paging_in, a);
- }
- gfn_unlock(p2m, gfn, 0);
- if ( rc < 0 )
- goto out_cancel;
-
- /* Pause domain if request came from guest and gfn has paging type */
- if ( p2m_is_paging(p2mt) && v->domain == d )
- {
- vm_event_vcpu_pause(v);
- req.flags |= VM_EVENT_FLAG_VCPU_PAUSED;
- }
- /* No need to inform pager if the gfn is not in the page-out path */
- else if ( p2mt != p2m_ram_paging_out && p2mt != p2m_ram_paged )
- {
- /* gfn is already on its way back and vcpu is not paused */
- out_cancel:
- vm_event_cancel_slot(d, d->vm_event_paging);
- return;
- }
-
- /* Send request to pager */
- req.u.mem_paging.p2mt = p2mt;
- req.vcpu_id = v->vcpu_id;
-
- vm_event_put_request(d, d->vm_event_paging, &req);
-}
-
-/**
- * p2m_mem_paging_prep - Allocate a new page for the guest
- * @d: guest domain
- * @gfn: guest page in paging state
- *
- * p2m_mem_paging_prep() will allocate a new page for the guest if the gfn is
- * not backed by a mfn. It is called by the pager.
- * It is required that the gfn was already populated. The gfn may already have
a
- * mfn if populate was called for gfn which was nominated but not evicted. In
- * this case only the p2mt needs to be forwarded.
- */
-int p2m_mem_paging_prep(struct domain *d, unsigned long gfn_l,
- XEN_GUEST_HANDLE_64(const_uint8) buffer)
-{
- struct page_info *page = NULL;
- p2m_type_t p2mt;
- p2m_access_t a;
- gfn_t gfn = _gfn(gfn_l);
- mfn_t mfn;
- struct p2m_domain *p2m = p2m_get_hostp2m(d);
- int ret, page_extant = 1;
-
- if ( !guest_handle_okay(buffer, PAGE_SIZE) )
- return -EINVAL;
-
- gfn_lock(p2m, gfn, 0);
-
- mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, 0, NULL, NULL);
-
- ret = -ENOENT;
- /* Allow missing pages */
- if ( (p2mt != p2m_ram_paging_in) && (p2mt != p2m_ram_paged) )
- goto out;
-
- /* Allocate a page if the gfn does not have one yet */
- if ( !mfn_valid(mfn) )
- {
- void *guest_map;
-
- /* If the user did not provide a buffer, we disallow */
- ret = -EINVAL;
- if ( unlikely(guest_handle_is_null(buffer)) )
- goto out;
- /* Get a free page */
- ret = -ENOMEM;
- page_alloc_mm_pre_lock(d);
- page = alloc_domheap_page(d, 0);
- if ( unlikely(page == NULL) )
- goto out;
- if ( unlikely(!get_page(page, d)) )
- {
- /*
- * The domain can't possibly know about this page yet, so failure
- * here is a clear indication of something fishy going on.
- */
- domain_crash(d);
- page = NULL;
- goto out;
- }
- mfn = page_to_mfn(page);
- page_extant = 0;
-
- guest_map = map_domain_page(mfn);
- ret = copy_from_guest(guest_map, buffer, PAGE_SIZE);
- unmap_domain_page(guest_map);
- if ( ret )
- {
- ret = -EFAULT;
- goto out;
- }
- }
-
- /* Make the page already guest-accessible. If the pager still has a
- * pending resume operation, it will be idempotent p2m entry-wise,
- * but will unpause the vcpu */
- ret = p2m_set_entry(p2m, gfn, mfn, PAGE_ORDER_4K,
- paging_mode_log_dirty(d) ? p2m_ram_logdirty
- : p2m_ram_rw, a);
- if ( !ret )
- {
- set_gpfn_from_mfn(mfn_x(mfn), gfn_l);
-
- if ( !page_extant )
- atomic_dec(&d->paged_pages);
- }
-
- out:
- gfn_unlock(p2m, gfn, 0);
-
- if ( page )
- {
- if ( ret )
- put_page_alloc_ref(page);
- put_page(page);
- }
-
- return ret;
-}
-
-/**
- * p2m_mem_paging_resume - Resume guest gfn
- * @d: guest domain
- * @rsp: vm_event response received
- *
- * p2m_mem_paging_resume() will forward the p2mt of a gfn to ram_rw. It is
- * called by the pager.
- *
- * The gfn was previously either evicted and populated, or nominated and
- * populated. If the page was evicted the p2mt will be p2m_ram_paging_in. If
- * the page was just nominated the p2mt will be p2m_ram_paging_in_start because
- * the pager did not call p2m_mem_paging_prep().
- *
- * If the gfn was dropped the vcpu needs to be unpaused.
- */
-
-void p2m_mem_paging_resume(struct domain *d, vm_event_response_t *rsp)
-{
- struct p2m_domain *p2m = p2m_get_hostp2m(d);
- p2m_type_t p2mt;
- p2m_access_t a;
- mfn_t mfn;
-
- /* Fix p2m entry if the page was not dropped */
- if ( !(rsp->u.mem_paging.flags & MEM_PAGING_DROP_PAGE) )
- {
- gfn_t gfn = _gfn(rsp->u.mem_access.gfn);
-
- gfn_lock(p2m, gfn, 0);
- mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, 0, NULL, NULL);
- /*
- * Allow only pages which were prepared properly, or pages which
- * were nominated but not evicted.
- */
- if ( mfn_valid(mfn) && (p2mt == p2m_ram_paging_in) )
- {
- int rc = p2m_set_entry(p2m, gfn, mfn, PAGE_ORDER_4K,
- paging_mode_log_dirty(d) ? p2m_ram_logdirty
:
- p2m_ram_rw, a);
-
- if ( !rc )
- set_gpfn_from_mfn(mfn_x(mfn), gfn_x(gfn));
- }
- gfn_unlock(p2m, gfn, 0);
- }
-}
-
#ifdef CONFIG_HVM
static struct p2m_domain *
p2m_getlru_nestedp2m(struct domain *d, struct p2m_domain *p2m)
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index baebc8b6ef..bf691ff568 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -731,18 +731,11 @@ static inline void p2m_pod_init(struct p2m_domain *p2m) {}
/* Modify p2m table for shared gfn */
int set_shared_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn);
-/* Check if a nominated gfn is valid to be paged out */
-int p2m_mem_paging_nominate(struct domain *d, unsigned long gfn);
-/* Evict a frame */
-int p2m_mem_paging_evict(struct domain *d, unsigned long gfn);
/* Tell xenpaging to drop a paged out frame */
void p2m_mem_paging_drop_page(struct domain *d, unsigned long gfn,
p2m_type_t p2mt);
/* Start populating a paged out frame */
void p2m_mem_paging_populate(struct domain *d, unsigned long gfn);
-/* Prepare the p2m for paging a frame in */
-int p2m_mem_paging_prep(struct domain *d, unsigned long gfn,
- XEN_GUEST_HANDLE_64(const_uint8) buffer);
/* Resume normal operation (in case a domain was paused) */
struct vm_event_st;
void p2m_mem_paging_resume(struct domain *d, struct vm_event_st *rsp);
--
generated by git-patchbot for /home/xen/git/xen.git#master
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