During creating of a HVM domU meminit_hvm() tries to map superpages.
After save/restore or migration this mapping is lost, everything is
allocated in single pages. This causes a performance degradition after
migration.
Add neccessary code to preallocate a superpage for the chunk of pfns
that is received. In case a pfn was not populated on the sending side it
must be freed on the receiving side to avoid over-allocation.
The existing code for x86_pv is moved unmodified into its own file.
Signed-off-by: Olaf Hering <o...@aepfle.de>
---
tools/libxc/xc_sr_common.h | 25 +++-
tools/libxc/xc_sr_restore.c | 75 +---------
tools/libxc/xc_sr_restore_x86_hvm.c | 288 ++++++++++++++++++++++++++++++++++++
tools/libxc/xc_sr_restore_x86_pv.c | 72 ++++++++-
4 files changed, 382 insertions(+), 78 deletions(-)
diff --git a/tools/libxc/xc_sr_common.h b/tools/libxc/xc_sr_common.h
index da2691ba79..0fa0fbea4d 100644
--- a/tools/libxc/xc_sr_common.h
+++ b/tools/libxc/xc_sr_common.h
@@ -139,6 +139,16 @@ struct xc_sr_restore_ops
*/
int (*setup)(struct xc_sr_context *ctx);
+ /**
+ * Populate PFNs
+ *
+ * Given a set of pfns, obtain memory from Xen to fill the physmap for the
+ * unpopulated subset.
+ */
+ int (*populate_pfns)(struct xc_sr_context *ctx, unsigned count,
+ const xen_pfn_t *original_pfns, const uint32_t
*types);
+
+
/**
* Process an individual record from the stream. The caller shall take
* care of processing common records (e.g. END, PAGE_DATA).
@@ -224,6 +234,8 @@ struct xc_sr_context
int send_back_fd;
unsigned long p2m_size;
+ unsigned long max_pages;
+ unsigned long tot_pages;
xc_hypercall_buffer_t dirty_bitmap_hbuf;
/* From Image Header. */
@@ -336,6 +348,11 @@ struct xc_sr_context
/* HVM context blob. */
void *context;
size_t contextsz;
+
+ /* Bitmap of currently allocated PFNs during restore. */
+ struct xc_sr_bitmap attempted_1g;
+ struct xc_sr_bitmap attempted_2m;
+ struct xc_sr_bitmap allocated_pfns;
} restore;
};
} x86_hvm;
@@ -455,14 +472,6 @@ static inline int write_record(struct xc_sr_context *ctx,
*/
int read_record(struct xc_sr_context *ctx, int fd, struct xc_sr_record *rec);
-/*
- * This would ideally be private in restore.c, but is needed by
- * x86_pv_localise_page() if we receive pagetables frames ahead of the
- * contents of the frames they point at.
- */
-int populate_pfns(struct xc_sr_context *ctx, unsigned count,
- const xen_pfn_t *original_pfns, const uint32_t *types);
-
#endif
/*
* Local variables:
diff --git a/tools/libxc/xc_sr_restore.c b/tools/libxc/xc_sr_restore.c
index d53948e1a6..8cd9289d1a 100644
--- a/tools/libxc/xc_sr_restore.c
+++ b/tools/libxc/xc_sr_restore.c
@@ -68,74 +68,6 @@ static int read_headers(struct xc_sr_context *ctx)
return 0;
}
-/*
- * Given a set of pfns, obtain memory from Xen to fill the physmap for the
- * unpopulated subset. If types is NULL, no page type checking is performed
- * and all unpopulated pfns are populated.
- */
-int populate_pfns(struct xc_sr_context *ctx, unsigned count,
- const xen_pfn_t *original_pfns, const uint32_t *types)
-{
- xc_interface *xch = ctx->xch;
- xen_pfn_t *mfns = malloc(count * sizeof(*mfns)),
- *pfns = malloc(count * sizeof(*pfns));
- unsigned i, nr_pfns = 0;
- int rc = -1;
-
- if ( !mfns || !pfns )
- {
- ERROR("Failed to allocate %zu bytes for populating the physmap",
- 2 * count * sizeof(*mfns));
- goto err;
- }
-
- for ( i = 0; i < count; ++i )
- {
- if ( (!types || (types &&
- (types[i] != XEN_DOMCTL_PFINFO_XTAB &&
- types[i] != XEN_DOMCTL_PFINFO_BROKEN))) &&
- !pfn_is_populated(ctx, original_pfns[i]) )
- {
- rc = pfn_set_populated(ctx, original_pfns[i]);
- if ( rc )
- goto err;
- pfns[nr_pfns] = mfns[nr_pfns] = original_pfns[i];
- ++nr_pfns;
- }
- }
-
- if ( nr_pfns )
- {
- rc = xc_domain_populate_physmap_exact(
- xch, ctx->domid, nr_pfns, 0, 0, mfns);
- if ( rc )
- {
- PERROR("Failed to populate physmap");
- goto err;
- }
-
- for ( i = 0; i < nr_pfns; ++i )
- {
- if ( mfns[i] == INVALID_MFN )
- {
- ERROR("Populate physmap failed for pfn %u", i);
- rc = -1;
- goto err;
- }
-
- ctx->restore.ops.set_gfn(ctx, pfns[i], mfns[i]);
- }
- }
-
- rc = 0;
-
- err:
- free(pfns);
- free(mfns);
-
- return rc;
-}
-
/*
* Given a list of pfns, their types, and a block of page data from the
* stream, populate and record their types, map the relevant subset and copy
@@ -161,7 +93,7 @@ static int process_page_data(struct xc_sr_context *ctx,
unsigned count,
goto err;
}
- rc = populate_pfns(ctx, count, pfns, types);
+ rc = ctx->restore.ops.populate_pfns(ctx, count, pfns, types);
if ( rc )
{
ERROR("Failed to populate pfns for batch of %u pages", count);
@@ -826,7 +758,12 @@ int xc_domain_restore(xc_interface *xch, int io_fd,
uint32_t dom,
return -1;
}
+ /* See xc_domain_getinfo */
+ ctx.restore.max_pages = ctx.dominfo.max_memkb >> (PAGE_SHIFT-10);
+ ctx.restore.tot_pages = ctx.dominfo.nr_pages;
ctx.restore.p2m_size = nr_pfns;
+ DPRINTF("dom %u p2m_size %lx max_pages %lx",
+ ctx.domid, ctx.restore.p2m_size, ctx.restore.max_pages);
if ( ctx.dominfo.hvm )
{
diff --git a/tools/libxc/xc_sr_restore_x86_hvm.c
b/tools/libxc/xc_sr_restore_x86_hvm.c
index 1dca85354a..2b0eca0c7c 100644
--- a/tools/libxc/xc_sr_restore_x86_hvm.c
+++ b/tools/libxc/xc_sr_restore_x86_hvm.c
@@ -135,6 +135,8 @@ static int x86_hvm_localise_page(struct xc_sr_context *ctx,
static int x86_hvm_setup(struct xc_sr_context *ctx)
{
xc_interface *xch = ctx->xch;
+ struct xc_sr_bitmap *bm;
+ unsigned long bits;
if ( ctx->restore.guest_type != DHDR_TYPE_X86_HVM )
{
@@ -149,7 +151,30 @@ static int x86_hvm_setup(struct xc_sr_context *ctx)
return -1;
}
+ bm = &ctx->x86_hvm.restore.attempted_1g;
+ bits = (ctx->restore.p2m_size >> SUPERPAGE_1GB_SHIFT) + 1;
+ if ( xc_sr_bitmap_resize(bm, bits) == false )
+ goto out;
+
+ bm = &ctx->x86_hvm.restore.attempted_2m;
+ bits = (ctx->restore.p2m_size >> SUPERPAGE_2MB_SHIFT) + 1;
+ if ( xc_sr_bitmap_resize(bm, bits) == false )
+ goto out;
+
+ bm = &ctx->x86_hvm.restore.allocated_pfns;
+ bits = ctx->restore.p2m_size + 1;
+ if ( xc_sr_bitmap_resize(bm, bits) == false )
+ goto out;
+
+ /* No superpage in 1st 2MB due to VGA hole */
+ xc_sr_set_bit(0, &ctx->x86_hvm.restore.attempted_1g);
+ xc_sr_set_bit(0, &ctx->x86_hvm.restore.attempted_2m);
+
return 0;
+
+out:
+ ERROR("Unable to allocate memory for pfn bitmaps");
+ return -1;
}
/*
@@ -224,10 +249,272 @@ static int x86_hvm_stream_complete(struct xc_sr_context
*ctx)
static int x86_hvm_cleanup(struct xc_sr_context *ctx)
{
free(ctx->x86_hvm.restore.context);
+ xc_sr_bitmap_free(&ctx->x86_hvm.restore.attempted_1g);
+ xc_sr_bitmap_free(&ctx->x86_hvm.restore.attempted_2m);
+ xc_sr_bitmap_free(&ctx->x86_hvm.restore.allocated_pfns);
return 0;
}
+/*
+ * Set a pfn as allocated, expanding the tracking structures if needed.
+ */
+static int pfn_set_allocated(struct xc_sr_context *ctx, xen_pfn_t pfn)
+{
+ xc_interface *xch = ctx->xch;
+
+ if ( !xc_sr_set_bit(pfn, &ctx->x86_hvm.restore.allocated_pfns) )
+ {
+ ERROR("Failed to realloc allocated_pfns bitmap");
+ errno = ENOMEM;
+ return -1;
+ }
+ return 0;
+}
+
+struct x86_hvm_sp {
+ xen_pfn_t pfn;
+ xen_pfn_t base_pfn;
+ unsigned long index;
+ unsigned long count;
+};
+
+/*
+ * Try to allocate a 1GB page for this pfn, but avoid Over-allocation.
+ * If this succeeds, mark the range of 2MB pages as busy.
+ */
+static bool x86_hvm_alloc_1g(struct xc_sr_context *ctx, struct x86_hvm_sp *sp)
+{
+ xc_interface *xch = ctx->xch;
+ struct xc_sr_bitmap *bm;
+ unsigned int order, shift;
+ int i, done;
+ xen_pfn_t extent;
+
+ bm = &ctx->x86_hvm.restore.attempted_1g;
+
+ /* Only one attempt to avoid overlapping allocation */
+ if ( xc_sr_test_and_set_bit(sp->index, bm) )
+ return false;
+
+ order = SUPERPAGE_1GB_SHIFT;
+ sp->count = 1ULL << order;
+
+ /* Allocate only if there is room for another superpage */
+ if ( ctx->restore.tot_pages + sp->count > ctx->restore.max_pages )
+ return false;
+
+ extent = sp->base_pfn = (sp->pfn >> order) << order;
+ done = xc_domain_populate_physmap(xch, ctx->domid, 1, order, 0, &extent);
+ if ( done < 0 ) {
+ PERROR("populate_physmap failed.");
+ return false;
+ }
+ if ( done == 0 )
+ return false;
+
+ DPRINTF("1G base_pfn %" PRI_xen_pfn "\n", sp->base_pfn);
+
+ /* Mark all 2MB pages as done to avoid overlapping allocation */
+ bm = &ctx->x86_hvm.restore.attempted_2m;
+ shift = SUPERPAGE_1GB_SHIFT - SUPERPAGE_2MB_SHIFT;
+ for ( i = 0; i < (sp->count >> shift); i++ )
+ xc_sr_set_bit((sp->base_pfn >> SUPERPAGE_2MB_SHIFT) + i, bm);
+
+ return true;
+}
+
+/* Allocate a 2MB page if x86_hvm_alloc_1g failed, avoid Over-allocation. */
+static bool x86_hvm_alloc_2m(struct xc_sr_context *ctx, struct x86_hvm_sp *sp)
+{
+ xc_interface *xch = ctx->xch;
+ struct xc_sr_bitmap *bm;
+ unsigned int order;
+ int done;
+ xen_pfn_t extent;
+
+ bm = &ctx->x86_hvm.restore.attempted_2m;
+
+ /* Only one attempt to avoid overlapping allocation */
+ if ( xc_sr_test_and_set_bit(sp->index, bm) )
+ return false;
+
+ order = SUPERPAGE_2MB_SHIFT;
+ sp->count = 1ULL << order;
+
+ /* Allocate only if there is room for another superpage */
+ if ( ctx->restore.tot_pages + sp->count > ctx->restore.max_pages )
+ return false;
+
+ extent = sp->base_pfn = (sp->pfn >> order) << order;
+ done = xc_domain_populate_physmap(xch, ctx->domid, 1, order, 0, &extent);
+ if ( done < 0 ) {
+ PERROR("populate_physmap failed.");
+ return false;
+ }
+ if ( done == 0 )
+ return false;
+
+ DPRINTF("2M base_pfn %" PRI_xen_pfn "\n", sp->base_pfn);
+ return true;
+}
+
+/* Allocate a single page if x86_hvm_alloc_2m failed. */
+static bool x86_hvm_alloc_4k(struct xc_sr_context *ctx, struct x86_hvm_sp *sp)
+{
+ xc_interface *xch = ctx->xch;
+ unsigned int order;
+ int done;
+ xen_pfn_t extent;
+
+ order = 0;
+ sp->count = 1ULL << order;
+
+ /* Allocate only if there is room for another page */
+ if ( ctx->restore.tot_pages + sp->count > ctx->restore.max_pages )
+ return false;
+
+ extent = sp->base_pfn = (sp->pfn >> order) << order;
+ done = xc_domain_populate_physmap(xch, ctx->domid, 1, order, 0, &extent);
+ if ( done < 0 ) {
+ PERROR("populate_physmap failed.");
+ return false;
+ }
+ if ( done == 0 )
+ return false;
+
+ DPRINTF("4K base_pfn %" PRI_xen_pfn "\n", sp->base_pfn);
+ return true;
+}
+/*
+ * Attempt to allocate a superpage where the pfn resides.
+ */
+static int x86_hvm_allocate_pfn(struct xc_sr_context *ctx, xen_pfn_t pfn)
+{
+ xc_interface *xch = ctx->xch;
+ bool success;
+ int rc = -1;
+ unsigned long idx_1g, idx_2m;
+ struct x86_hvm_sp sp = {
+ .pfn = pfn
+ };
+
+ if ( xc_sr_test_bit(pfn, &ctx->x86_hvm.restore.allocated_pfns) )
+ return 0;
+
+ idx_1g = pfn >> SUPERPAGE_1GB_SHIFT;
+ idx_2m = pfn >> SUPERPAGE_2MB_SHIFT;
+ if ( !xc_sr_bitmap_resize(&ctx->x86_hvm.restore.attempted_1g, idx_1g) )
+ {
+ PERROR("Failed to realloc attempted_1g");
+ return -1;
+ }
+ if ( !xc_sr_bitmap_resize(&ctx->x86_hvm.restore.attempted_2m, idx_2m) )
+ {
+ PERROR("Failed to realloc attempted_2m");
+ return -1;
+ }
+
+ sp.index = idx_1g;
+ success = x86_hvm_alloc_1g(ctx, &sp);
+
+ if ( success == false ) {
+ sp.index = idx_2m;
+ success = x86_hvm_alloc_2m(ctx, &sp);
+ }
+
+ if ( success == false ) {
+ sp.index = 0;
+ success = x86_hvm_alloc_4k(ctx, &sp);
+ }
+
+ if ( success == true ) {
+ do {
+ sp.count--;
+ ctx->restore.tot_pages++;
+ rc = pfn_set_allocated(ctx, sp.base_pfn + sp.count);
+ if ( rc )
+ break;
+ } while ( sp.count );
+ }
+ return rc;
+}
+
+static int x86_hvm_populate_pfns(struct xc_sr_context *ctx, unsigned count,
+ const xen_pfn_t *original_pfns,
+ const uint32_t *types)
+{
+ xc_interface *xch = ctx->xch;
+ xen_pfn_t pfn, min_pfn = original_pfns[0], max_pfn = original_pfns[0];
+ unsigned i, freed = 0, order;
+ int rc = -1;
+
+ for ( i = 0; i < count; ++i )
+ {
+ if ( original_pfns[i] < min_pfn )
+ min_pfn = original_pfns[i];
+ if ( original_pfns[i] > max_pfn )
+ max_pfn = original_pfns[i];
+ }
+ DPRINTF("batch of %u pfns between %" PRI_xen_pfn " %" PRI_xen_pfn "\n",
+ count, min_pfn, max_pfn);
+
+ for ( i = 0; i < count; ++i )
+ {
+ if ( (types[i] != XEN_DOMCTL_PFINFO_XTAB &&
+ types[i] != XEN_DOMCTL_PFINFO_BROKEN) &&
+ !pfn_is_populated(ctx, original_pfns[i]) )
+ {
+ rc = x86_hvm_allocate_pfn(ctx, original_pfns[i]);
+ if ( rc )
+ goto err;
+ rc = pfn_set_populated(ctx, original_pfns[i]);
+ if ( rc )
+ goto err;
+ }
+ }
+
+ /*
+ * Scan the entire superpage because several batches will fit into
+ * a superpage, and it is unknown which pfn triggered the allocation.
+ */
+ order = SUPERPAGE_1GB_SHIFT;
+ pfn = min_pfn = (min_pfn >> order) << order;
+
+ while ( pfn <= max_pfn )
+ {
+ struct xc_sr_bitmap *bm;
+ bm = &ctx->x86_hvm.restore.allocated_pfns;
+ if ( !xc_sr_bitmap_resize(bm, pfn) )
+ {
+ PERROR("Failed to realloc allocated_pfns %" PRI_xen_pfn, pfn);
+ goto err;
+ }
+ if ( !pfn_is_populated(ctx, pfn) &&
+ xc_sr_test_and_clear_bit(pfn, bm) ) {
+ xen_pfn_t p = pfn;
+ rc = xc_domain_decrease_reservation_exact(xch, ctx->domid, 1, 0,
&p);
+ if ( rc )
+ {
+ PERROR("Failed to release pfn %" PRI_xen_pfn, pfn);
+ goto err;
+ }
+ ctx->restore.tot_pages--;
+ freed++;
+ }
+ pfn++;
+ }
+ if ( freed )
+ DPRINTF("freed %u between %" PRI_xen_pfn " %" PRI_xen_pfn "\n",
+ freed, min_pfn, max_pfn);
+
+ rc = 0;
+
+ err:
+ return rc;
+}
+
+
struct xc_sr_restore_ops restore_ops_x86_hvm =
{
.pfn_is_valid = x86_hvm_pfn_is_valid,
@@ -236,6 +523,7 @@ struct xc_sr_restore_ops restore_ops_x86_hvm =
.set_page_type = x86_hvm_set_page_type,
.localise_page = x86_hvm_localise_page,
.setup = x86_hvm_setup,
+ .populate_pfns = x86_hvm_populate_pfns,
.process_record = x86_hvm_process_record,
.stream_complete = x86_hvm_stream_complete,
.cleanup = x86_hvm_cleanup,
diff --git a/tools/libxc/xc_sr_restore_x86_pv.c
b/tools/libxc/xc_sr_restore_x86_pv.c
index 50e25c162c..87957559bc 100644
--- a/tools/libxc/xc_sr_restore_x86_pv.c
+++ b/tools/libxc/xc_sr_restore_x86_pv.c
@@ -936,6 +936,75 @@ static void x86_pv_set_gfn(struct xc_sr_context *ctx,
xen_pfn_t pfn,
((uint32_t *)ctx->x86_pv.p2m)[pfn] = mfn;
}
+/*
+ * Given a set of pfns, obtain memory from Xen to fill the physmap for the
+ * unpopulated subset. If types is NULL, no page type checking is performed
+ * and all unpopulated pfns are populated.
+ */
+static int x86_pv_populate_pfns(struct xc_sr_context *ctx, unsigned count,
+ const xen_pfn_t *original_pfns,
+ const uint32_t *types)
+{
+ xc_interface *xch = ctx->xch;
+ xen_pfn_t *mfns = malloc(count * sizeof(*mfns)),
+ *pfns = malloc(count * sizeof(*pfns));
+ unsigned i, nr_pfns = 0;
+ int rc = -1;
+
+ if ( !mfns || !pfns )
+ {
+ ERROR("Failed to allocate %zu bytes for populating the physmap",
+ 2 * count * sizeof(*mfns));
+ goto err;
+ }
+
+ for ( i = 0; i < count; ++i )
+ {
+ if ( (!types || (types &&
+ (types[i] != XEN_DOMCTL_PFINFO_XTAB &&
+ types[i] != XEN_DOMCTL_PFINFO_BROKEN))) &&
+ !pfn_is_populated(ctx, original_pfns[i]) )
+ {
+ rc = pfn_set_populated(ctx, original_pfns[i]);
+ if ( rc )
+ goto err;
+ pfns[nr_pfns] = mfns[nr_pfns] = original_pfns[i];
+ ++nr_pfns;
+ }
+ }
+
+ if ( nr_pfns )
+ {
+ rc = xc_domain_populate_physmap_exact(
+ xch, ctx->domid, nr_pfns, 0, 0, mfns);
+ if ( rc )
+ {
+ PERROR("Failed to populate physmap");
+ goto err;
+ }
+
+ for ( i = 0; i < nr_pfns; ++i )
+ {
+ if ( mfns[i] == INVALID_MFN )
+ {
+ ERROR("Populate physmap failed for pfn %u", i);
+ rc = -1;
+ goto err;
+ }
+
+ ctx->restore.ops.set_gfn(ctx, pfns[i], mfns[i]);
+ }
+ }
+
+ rc = 0;
+
+ err:
+ free(pfns);
+ free(mfns);
+
+ return rc;
+}
+
/*
* restore_ops function. Convert pfns back to mfns in pagetables. Possibly
* needs to populate new frames if a PTE is found referring to a frame which
@@ -980,7 +1049,7 @@ static int x86_pv_localise_page(struct xc_sr_context *ctx,
}
}
- if ( to_populate && populate_pfns(ctx, to_populate, pfns, NULL) )
+ if ( to_populate && x86_pv_populate_pfns(ctx, to_populate, pfns, NULL) )
return -1;
for ( i = 0; i < (PAGE_SIZE / sizeof(uint64_t)); ++i )
@@ -1160,6 +1229,7 @@ struct xc_sr_restore_ops restore_ops_x86_pv =
.set_gfn = x86_pv_set_gfn,
.localise_page = x86_pv_localise_page,
.setup = x86_pv_setup,
+ .populate_pfns = x86_pv_populate_pfns,
.process_record = x86_pv_process_record,
.stream_complete = x86_pv_stream_complete,
.cleanup = x86_pv_cleanup,
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