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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v6 6/8] xen/arm: introduce GNTTABOP_cache_flush
Introduce a new hypercall to perform cache maintenance operation on
behalf of the guest. The argument is a machine address and a size. The
implementation checks that the memory range is owned by the guest or the
guest has been granted access to it by another domain.
Introduce grant_map_exists: an internal grant table function to check
whether an mfn has been granted to a given domain on a target grant
table.
As grant_map_exists loops over all the guest grant table entries, limit
DEFAULT_MAX_NR_GRANT_FRAMES to 10 to cap the loop to 5000 iterations
max. Warn if the user sets max_grant_frames higher than 10.
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
Changes in v6:
- set DEFAULT_MAX_NR_GRANT_FRAMES to 10;
- warn if max_grant_frames > 10.
Changes in v5:
- make mfn mfn unsigned long;
- remove unhelpful error message;
- handle errors returned by cache maintenance functions.
Changes in v4:
- ASSERT(spin_is_locked);
- return instead of break in grant_map_exists;
- pass a pointer to __gnttab_cache_flush;
- code style;
- unsigned int iterator in gnttab_cache_flush;
- return ret instead -ret;
- cflush.offset >= PAGE_SIZE return -EINVAL.
Changes in v3:
- reduce the time the grant_table lock is held;
- fix warning message;
- s/EFAULT/EPERM;
- s/llx/PRIx64;
- check offset and size independetly before checking their sum;
- rcu_lock_current_domain cannot fail;
- s/ENOSYS/EOPNOTSUPP;
- use clean_and_invalidate_xen_dcache_va_range to do both operations at
once;
- fold grant_map_exists in this patch;
- support "count" argument;
- make correspondent changes to compat/grant_table.c;
- introduce GNTTAB_CACHE_SOURCE_GREF to select the type of input in the
union;
- rename size field to length;
- make length and offset uint16_t;
- only take spin_lock if d != owner.
Changes in v2:
- do not check for mfn_to_page errors;
- take a reference to the page;
- replace printk with gdprintk;
- split long line;
- remove out label;
- move rcu_lock_current_domain down before the loop.
- move the hypercall to GNTTABOP;
- take a spin_lock before calling grant_map_exists.
---
xen/common/compat/grant_table.c | 8 +++
xen/common/grant_table.c | 137 ++++++++++++++++++++++++++++++++++++++
xen/include/public/grant_table.h | 20 ++++++
xen/include/xen/grant_table.h | 2 +-
xen/include/xlat.lst | 1 +
5 files changed, 167 insertions(+), 1 deletion(-)
diff --git a/xen/common/compat/grant_table.c b/xen/common/compat/grant_table.c
index 2dc1e44..5130c35 100644
--- a/xen/common/compat/grant_table.c
+++ b/xen/common/compat/grant_table.c
@@ -51,6 +51,10 @@ CHECK_gnttab_get_version;
CHECK_gnttab_swap_grant_ref;
#undef xen_gnttab_swap_grant_ref
+#define xen_gnttab_cache_flush gnttab_cache_flush
+CHECK_gnttab_cache_flush;
+#undef xen_gnttab_cache_flush
+
int compat_grant_table_op(unsigned int cmd,
XEN_GUEST_HANDLE_PARAM(void) cmp_uop,
unsigned int count)
@@ -106,6 +110,10 @@ int compat_grant_table_op(unsigned int cmd,
CASE(swap_grant_ref);
#endif
+#ifndef CHECK_gnttab_cache_flush
+ CASE(cache_flush);
+#endif
+
#undef CASE
default:
return do_grant_table_op(cmd, cmp_uop, count);
diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index 345be82..2124444 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -489,6 +489,34 @@ static int _set_status(unsigned gt_version,
return _set_status_v2(domid, readonly, mapflag, shah, act, status);
}
+static bool_t grant_map_exists(const struct domain *ld,
+ struct grant_table *rgt,
+ unsigned long mfn)
+{
+ const struct active_grant_entry *act;
+ grant_ref_t ref;
+
+ ASSERT(spin_is_locked(&rgt->lock));
+
+ for ( ref = 0; ref != nr_grant_entries(rgt); ref++ )
+ {
+ act = &active_entry(rgt, ref);
+
+ if ( !act->pin )
+ continue;
+
+ if ( act->domid != ld->domain_id )
+ continue;
+
+ if ( act->frame != mfn )
+ continue;
+
+ return 1;
+ }
+
+ return 0;
+}
+
static void mapcount(
struct grant_table *lgt, struct domain *rd, unsigned long mfn,
unsigned int *wrc, unsigned int *rdc)
@@ -2487,6 +2515,97 @@
gnttab_swap_grant_ref(XEN_GUEST_HANDLE_PARAM(gnttab_swap_grant_ref_t) uop,
return 0;
}
+static int __gnttab_cache_flush(gnttab_cache_flush_t *cflush)
+{
+ struct domain *d, *owner;
+ struct page_info *page;
+ unsigned long mfn;
+ void *v;
+ int ret = 0;
+
+ if ( (cflush->offset >= PAGE_SIZE) ||
+ (cflush->length > PAGE_SIZE) ||
+ (cflush->offset + cflush->length > PAGE_SIZE) )
+ return -EINVAL;
+
+ if ( cflush->length == 0 || cflush->op == 0 )
+ return 0;
+
+ /* currently unimplemented */
+ if ( cflush->op & GNTTAB_CACHE_SOURCE_GREF )
+ return -EOPNOTSUPP;
+
+ d = rcu_lock_current_domain();
+ mfn = cflush->a.dev_bus_addr >> PAGE_SHIFT;
+
+ if ( !mfn_valid(mfn) )
+ {
+ rcu_unlock_domain(d);
+ return -EINVAL;
+ }
+
+ page = mfn_to_page(mfn);
+ owner = page_get_owner_and_reference(page);
+ if ( !owner )
+ {
+ rcu_unlock_domain(d);
+ return -EPERM;
+ }
+
+ if ( d != owner )
+ {
+ spin_lock(&owner->grant_table->lock);
+
+ if ( !grant_map_exists(d, owner->grant_table, mfn) )
+ {
+ spin_unlock(&owner->grant_table->lock);
+ rcu_unlock_domain(d);
+ put_page(page);
+ return -EINVAL;
+ }
+ }
+
+ v = map_domain_page(mfn);
+ v += cflush->offset;
+
+ if ( (cflush->op & GNTTAB_CACHE_INVAL) && (cflush->op &
GNTTAB_CACHE_CLEAN) )
+ ret = clean_and_invalidate_dcache_va_range(v, cflush->length);
+ else if ( cflush->op & GNTTAB_CACHE_INVAL )
+ ret = invalidate_dcache_va_range(v, cflush->length);
+ else if ( cflush->op & GNTTAB_CACHE_CLEAN )
+ ret = clean_dcache_va_range(v, cflush->length);
+
+ if ( d != owner )
+ spin_unlock(&owner->grant_table->lock);
+ unmap_domain_page(v);
+ put_page(page);
+
+ return ret;
+}
+
+static long
+gnttab_cache_flush(XEN_GUEST_HANDLE_PARAM(gnttab_cache_flush_t) uop,
+ unsigned int count)
+{
+ int ret;
+ unsigned int i;
+ gnttab_cache_flush_t op;
+
+ for ( i = 0; i < count; i++ )
+ {
+ if ( i && hypercall_preempt_check() )
+ return i;
+ if ( unlikely(__copy_from_guest(&op, uop, 1)) )
+ return -EFAULT;
+ ret = __gnttab_cache_flush(&op);
+ if ( ret < 0 )
+ return ret;
+ guest_handle_add_offset(uop, 1);
+ }
+ return 0;
+}
+
+
long
do_grant_table_op(
unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) uop, unsigned int count)
@@ -2616,6 +2735,20 @@ do_grant_table_op(
}
break;
}
+ case GNTTABOP_cache_flush:
+ {
+ XEN_GUEST_HANDLE_PARAM(gnttab_cache_flush_t) cflush =
+ guest_handle_cast(uop, gnttab_cache_flush_t);
+ if ( unlikely(!guest_handle_okay(cflush, count)) )
+ goto out;
+ rc = gnttab_cache_flush(cflush, count);
+ if ( rc > 0 )
+ {
+ guest_handle_add_offset(cflush, rc);
+ uop = guest_handle_cast(cflush, void);
+ }
+ break;
+ }
default:
rc = -ENOSYS;
break;
@@ -2953,6 +3086,10 @@ static int __init gnttab_usage_init(void)
if ( !max_maptrack_frames )
max_maptrack_frames = MAX_MAPTRACK_TO_GRANTS_RATIO * max_grant_frames;
+ if ( max_grant_frames > DEFAULT_MAX_NR_GRANT_FRAMES )
+ printk(XENLOG_WARNING "An high gnttab_max_frames can seriously slow
down the hypervisor.\n"
+ "It is recommended to set gnttab_max_frames to %d max.\n",
DEFAULT_MAX_NR_GRANT_FRAMES);
+
register_keyhandler('g', &gnttab_usage_print_all_keyhandler);
return 0;
}
diff --git a/xen/include/public/grant_table.h b/xen/include/public/grant_table.h
index b8a3d6c..20d4e77 100644
--- a/xen/include/public/grant_table.h
+++ b/xen/include/public/grant_table.h
@@ -309,6 +309,7 @@ typedef uint16_t grant_status_t;
#define GNTTABOP_get_status_frames 9
#define GNTTABOP_get_version 10
#define GNTTABOP_swap_grant_ref 11
+#define GNTTABOP_cache_flush 12
#endif /* __XEN_INTERFACE_VERSION__ */
/* ` } */
@@ -574,6 +575,25 @@ struct gnttab_swap_grant_ref {
typedef struct gnttab_swap_grant_ref gnttab_swap_grant_ref_t;
DEFINE_XEN_GUEST_HANDLE(gnttab_swap_grant_ref_t);
+/*
+ * Issue one or more cache maintenance operations on a portion of a
+ * page granted to the calling domain by a foreign domain.
+ */
+struct gnttab_cache_flush {
+ union {
+ uint64_t dev_bus_addr;
+ grant_ref_t ref;
+ } a;
+ uint16_t offset; /* offset from start of grant */
+ uint16_t length; /* size within the grant */
+#define GNTTAB_CACHE_CLEAN (1<<0)
+#define GNTTAB_CACHE_INVAL (1<<1)
+#define GNTTAB_CACHE_SOURCE_GREF (1<<31)
+ uint32_t op;
+};
+typedef struct gnttab_cache_flush gnttab_cache_flush_t;
+DEFINE_XEN_GUEST_HANDLE(gnttab_cache_flush_t);
+
#endif /* __XEN_INTERFACE_VERSION__ */
/*
diff --git a/xen/include/xen/grant_table.h b/xen/include/xen/grant_table.h
index 9f3a1f3..77328cd 100644
--- a/xen/include/xen/grant_table.h
+++ b/xen/include/xen/grant_table.h
@@ -47,7 +47,7 @@
#ifndef DEFAULT_MAX_NR_GRANT_FRAMES /* to allow arch to override */
/* Default maximum size of a grant table. [POLICY] */
-#define DEFAULT_MAX_NR_GRANT_FRAMES 32
+#define DEFAULT_MAX_NR_GRANT_FRAMES 10
#endif
#ifndef max_nr_grant_frames /* to allow arch to override */
/* The maximum size of a grant table. */
diff --git a/xen/include/xlat.lst b/xen/include/xlat.lst
index 234b668..9ce9fee 100644
--- a/xen/include/xlat.lst
+++ b/xen/include/xlat.lst
@@ -51,6 +51,7 @@
? grant_entry_header grant_table.h
? grant_entry_v2 grant_table.h
? gnttab_swap_grant_ref grant_table.h
+? gnttab_cache_flush grant_table.h
? kexec_exec kexec.h
! kexec_image kexec.h
! kexec_range kexec.h
--
1.7.10.4
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