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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v9 3/7] libxl: support mapping static shared memory areas during domain creation
From: Zhongze Liu <blackskygg@xxxxxxxxx>
Add libxl__sshm_add to map shared pages from one DomU to another, The mapping
process involves the following steps:
* Set defaults and check for further errors in the static_shm configs:
overlapping areas, invalid ranges, duplicated owner domain,
not page aligned, no owner domain etc.
* Use xc_domain_add_to_physmap_batch to map the shared pages to borrowers
* When some of the pages can't be successfully mapped, roll back any
successfully mapped pages so that the system stays in a consistent state.
* Write information about static shared memory areas into the appropriate
xenstore paths and set the refcount of the shared region accordingly.
Temporarily mark this as unsupported on x86 because calling p2m_add_foreign on
two domU's is currently not allowd on x86 (see the comments in
x86/mm/p2m.c:p2m_add_foreign for more details).
This is for the proposal "Allow setting up shared memory areas between VMs
from xl config file" (see [1]).
[1] https://lists.xen.org/archives/html/xen-devel/2017-08/msg03242.html
Signed-off-by: Zhongze Liu <blackskygg@xxxxxxxxx>
Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>
Cc: xen-devel@xxxxxxxxxxxxx
---
Changes in v9:
- rename master to owner and slave to borrower
- use libxl__xs_read_checked
- move call to libxl__sshm_do_map after xenstore transaction
- improve in-code comment
- remove useless isretry variable
- check for count_string != NULL before proceeding
Changes in v5:
- fix typos
- add comments
- add value checks (including alignment checks) in sshm_setdefaults
---
tools/libxl/Makefile | 3 +-
tools/libxl/libxl_arch.h | 6 +
tools/libxl/libxl_arm.c | 15 ++
tools/libxl/libxl_create.c | 27 +++
tools/libxl/libxl_internal.h | 14 ++
tools/libxl/libxl_sshm.c | 399 +++++++++++++++++++++++++++++++++++++++++++
tools/libxl/libxl_x86.c | 19 +++
7 files changed, 482 insertions(+), 1 deletion(-)
create mode 100644 tools/libxl/libxl_sshm.c
diff --git a/tools/libxl/Makefile b/tools/libxl/Makefile
index 6da342e..53af186 100644
--- a/tools/libxl/Makefile
+++ b/tools/libxl/Makefile
@@ -140,7 +140,8 @@ LIBXL_OBJS = flexarray.o libxl.o libxl_create.o libxl_dm.o
libxl_pci.o \
libxl_vtpm.o libxl_nic.o libxl_disk.o libxl_console.o \
libxl_cpupool.o libxl_mem.o libxl_sched.o libxl_tmem.o \
libxl_9pfs.o libxl_domain.o libxl_vdispl.o \
- libxl_pvcalls.o libxl_vsnd.o libxl_vkb.o $(LIBXL_OBJS-y)
+ libxl_pvcalls.o libxl_vsnd.o libxl_vkb.o libxl_sshm.o \
+ $(LIBXL_OBJS-y)
LIBXL_OBJS += libxl_genid.o
LIBXL_OBJS += _libxl_types.o libxl_flask.o _libxl_types_internal.o
diff --git a/tools/libxl/libxl_arch.h b/tools/libxl/libxl_arch.h
index 930570e..63c26cc 100644
--- a/tools/libxl/libxl_arch.h
+++ b/tools/libxl/libxl_arch.h
@@ -73,6 +73,12 @@ int libxl__arch_extra_memory(libxl__gc *gc,
const libxl_domain_build_info *info,
uint64_t *out);
+_hidden
+bool libxl__arch_domain_support_sshm(const libxl_domain_build_info *b_info);
+
+_hidden
+int libxl__arch_domain_sshm_cachepolicy_setdefault(libxl_static_shm *sshm);
+
#if defined(__i386__) || defined(__x86_64__)
#define LAPIC_BASE_ADDRESS 0xfee00000
diff --git a/tools/libxl/libxl_arm.c b/tools/libxl/libxl_arm.c
index 25dc3de..054ad58 100644
--- a/tools/libxl/libxl_arm.c
+++ b/tools/libxl/libxl_arm.c
@@ -1138,6 +1138,21 @@ void libxl__arch_domain_build_info_setdefault(libxl__gc
*gc,
libxl_domain_build_info_init_type(b_info, LIBXL_DOMAIN_TYPE_PVH);
}
+bool libxl__arch_domain_support_sshm(const libxl_domain_build_info *b_info)
+{
+ return true;
+}
+
+int libxl__arch_domain_sshm_cachepolicy_setdefault(libxl_static_shm *sshm)
+{
+ if (sshm->cache_policy == LIBXL_SSHM_CACHEPOLICY_UNKNOWN)
+ sshm->cache_policy = LIBXL_SSHM_CACHEPOLICY_ARM_NORMAL;
+ if (sshm->cache_policy >= LIBXL_SSHM_CACHEPOLICY_X86_NORMAL)
+ return ERROR_INVAL;
+
+ return 0;
+}
+
/*
* Local variables:
* mode: C
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 320dbed..45ae9e4 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -513,6 +513,14 @@ int libxl__domain_build(libxl__gc *gc,
ret = ERROR_INVAL;
goto out;
}
+
+ /* The p2m has been setup, we could map the static shared memory now. */
+ ret = libxl__sshm_add(gc, domid, d_config->sshms, d_config->num_sshms);
+ if (ret != 0) {
+ LOG(ERROR, "failed to map static shared memory");
+ goto out;
+ }
+
ret = libxl__build_post(gc, domid, info, state, vments, localents);
out:
return ret;
@@ -949,6 +957,25 @@ static void initiate_domain_create(libxl__egc *egc,
goto error_out;
}
+ if (d_config->num_sshms != 0 &&
+ !libxl__arch_domain_support_sshm(&d_config->b_info)) {
+ LOGD(ERROR, domid, "static_shm is not supported by this domain type.");
+ ret = ERROR_INVAL;
+ goto error_out;
+ }
+
+ for (i = 0; i < d_config->num_sshms; ++i) {
+ ret = libxl__sshm_setdefault(gc, domid, &d_config->sshms[i]);
+ if (ret) {
+ LOGD(ERROR, domid, "Unable to set defaults for static shm");
+ goto error_out;
+ }
+ }
+
+ ret = libxl__sshm_check_overlap(gc, domid,
+ d_config->sshms, d_config->num_sshms);
+ if (ret) goto error_out;
+
ret = libxl__domain_make(gc, d_config, &dcs->build_state, &domid);
if (ret) {
LOGD(ERROR, domid, "cannot make domain: %d", ret);
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 43947b1..6f31a3d 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -4434,6 +4434,20 @@ static inline const char *libxl__qemu_qmp_path(libxl__gc
*gc, int domid)
#endif
/*
+ * Set up static shared ram pages for HVM domains to communicate
+ *
+ * This function should only be called after the memory map is constructed
+ * and before any further memory access.
+ */
+_hidden int libxl__sshm_add(libxl__gc *gc, uint32_t domid,
+ libxl_static_shm *sshm, int len);
+
+_hidden int libxl__sshm_check_overlap(libxl__gc *gc, uint32_t domid,
+ libxl_static_shm *sshms, int len);
+_hidden int libxl__sshm_setdefault(libxl__gc *gc, uint32_t domid,
+ libxl_static_shm *sshm);
+
+/*
* Local variables:
* mode: C
* c-basic-offset: 4
diff --git a/tools/libxl/libxl_sshm.c b/tools/libxl/libxl_sshm.c
new file mode 100644
index 0000000..d00981b
--- /dev/null
+++ b/tools/libxl/libxl_sshm.c
@@ -0,0 +1,399 @@
+#include "libxl_osdeps.h"
+#include "libxl_internal.h"
+#include "libxl_arch.h"
+
+#define SSHM_PATH(id) GCSPRINTF("/libxl/static_shm/%s", id)
+
+#define SSHM_ERROR(domid, sshmid, f, ...) \
+ LOGD(ERROR, domid, "static_shm id = %s: " f, sshmid, ##__VA_ARGS__)
+
+
+/* Set default values for libxl_static_shm */
+int libxl__sshm_setdefault(libxl__gc *gc, uint32_t domid,
+ libxl_static_shm *sshm)
+{
+ int rc;
+
+ if (sshm->role != LIBXL_SSHM_ROLE_BORROWER &&
+ sshm->role != LIBXL_SSHM_ROLE_OWNER)
+ return ERROR_INVAL;
+ if (sshm->begin & ~XC_PAGE_MASK ||
+ sshm->size & ~XC_PAGE_MASK ||
+ (sshm->offset != LIBXL_SSHM_RANGE_UNKNOWN &&
+ sshm->offset & ~XC_PAGE_MASK)) {
+ SSHM_ERROR(domid, sshm->id,
+ "begin/size/offset is not a multiple of 4K");
+ return ERROR_INVAL;
+ }
+
+ /* role-specific checks */
+ if (sshm->role == LIBXL_SSHM_ROLE_BORROWER) {
+ if (sshm->offset == LIBXL_SSHM_RANGE_UNKNOWN)
+ sshm->offset = 0;
+ if (sshm->cache_policy != LIBXL_SSHM_CACHEPOLICY_UNKNOWN) {
+ SSHM_ERROR(domid, sshm->id,
+ "cache_policy is only applicable to owner domains");
+ rc = ERROR_INVAL;
+ goto out;
+ }
+ } else {
+ if (sshm->offset != LIBXL_SSHM_RANGE_UNKNOWN) {
+ SSHM_ERROR(domid, sshm->id,
+ "offset is only applicable to borrower domains");
+ rc = ERROR_INVAL;
+ goto out;
+ }
+
+ rc = libxl__arch_domain_sshm_cachepolicy_setdefault(sshm);
+ if (rc) {
+ SSHM_ERROR(domid, sshm->id,
+ "cache policy not supported on this platform");
+ goto out;
+ }
+ }
+
+ rc = 0;
+out:
+ return rc;
+}
+
+/* Comparator for sorting sshm ranges by sshm->begin */
+static int sshm_range_cmp(const void *a, const void *b)
+{
+ libxl_static_shm *const *sshma = a, *const *sshmb = b;
+ return (*sshma)->begin > (*sshmb)->begin ? 1 : -1;
+}
+
+/* Check if the sshm borrower configs in @sshm overlap */
+int libxl__sshm_check_overlap(libxl__gc *gc, uint32_t domid,
+ libxl_static_shm *sshms, int len)
+{
+
+ const libxl_static_shm **borrower_sshms = NULL;
+ int num_borrowers;
+ int i;
+
+ if (!len) return 0;
+
+ borrower_sshms = libxl__calloc(gc, len, sizeof(borrower_sshms[0]));
+ num_borrowers = 0;
+ for (i = 0; i < len; ++i) {
+ if (sshms[i].role == LIBXL_SSHM_ROLE_BORROWER)
+ borrower_sshms[num_borrowers++] = sshms + i;
+ }
+ qsort(borrower_sshms, num_borrowers, sizeof(borrower_sshms[0]),
sshm_range_cmp);
+
+ for (i = 0; i < num_borrowers - 1; ++i) {
+ if (borrower_sshms[i+1]->begin <
+ borrower_sshms[i]->begin + borrower_sshms[i]->size) {
+ SSHM_ERROR(domid, borrower_sshms[i+1]->id, "borrower ranges
overlap.");
+ return ERROR_INVAL;
+ }
+ }
+
+ return 0;
+}
+
+/* libxl__sshm_do_map -- map pages into borrower's physmap
+ *
+ * This functions maps
+ * owner gfn: [@msshm->begin + @sshm->offset,
+ * @msshm->begin + @msshm->size + @sshm->offset)
+ * into
+ * borrower gfn: [@sshm->begin, @sshm->begin + @sshm->size)
+ *
+ * The gfns of the pages that are successfully mapped will be stored
+ * in @mapped, and the number of the gfns will be stored in @nmapped.
+ *
+ * The caller has to guarantee that all the values are page-aligned.
+ */
+static int libxl__sshm_do_map(libxl__gc *gc, uint32_t mid, uint32_t sid,
+ libxl_static_shm *sshm, libxl_static_shm *msshm,
+ xen_pfn_t *mapped, unsigned int *nmapped)
+{
+ int rc;
+ int i;
+ xen_pfn_t num_mpages, num_spages, num_success, offset;
+ int *errs;
+ xen_ulong_t *idxs;
+ xen_pfn_t *gpfns;
+
+ num_mpages = (msshm->size) >> XC_PAGE_SHIFT;
+ num_spages = (sshm->size) >> XC_PAGE_SHIFT;
+ offset = sshm->offset >> XC_PAGE_SHIFT;
+
+ /* Check range. Test offset < mpages first to avoid overflow */
+ if ((offset >= num_mpages) || (num_mpages - offset < num_spages)) {
+ SSHM_ERROR(sid, sshm->id, "exceeds owner's address space.");
+ rc = ERROR_INVAL;
+ goto out;
+ }
+
+ /* fill out the gfn's and do the mapping */
+ errs = libxl__calloc(gc, num_spages, sizeof(int));
+ idxs = libxl__calloc(gc, num_spages, sizeof(xen_ulong_t));
+ gpfns = libxl__calloc(gc, num_spages, sizeof(xen_pfn_t));
+ for (i = 0; i < num_spages; i++) {
+ idxs[i] = (msshm->begin >> XC_PAGE_SHIFT) + offset + i;
+ gpfns[i]= (sshm->begin >> XC_PAGE_SHIFT) + i;
+ }
+ rc = xc_domain_add_to_physmap_batch(CTX->xch,
+ sid, mid,
+ XENMAPSPACE_gmfn_share,
+ num_spages,
+ idxs, gpfns, errs);
+
+ num_success = 0;
+ for (i = 0; i < num_spages; i++) {
+ if (errs[i]) {
+ SSHM_ERROR(sid, sshm->id,
+ "can't map at address 0x%"PRIx64".",
+ gpfns[i] << XC_PAGE_SHIFT);
+ rc = ERROR_FAIL;
+ } else {
+ mapped[num_success++] = gpfns[i];
+ }
+ }
+ *nmapped = num_success;
+ if (rc) goto out;
+
+ rc = 0;
+out:
+ return rc;
+}
+
+/* Xenstore ops are protected by a transaction */
+static int libxl__sshm_incref(libxl__gc *gc, xs_transaction_t xt,
+ const char *sshm_path)
+{
+ int rc, count;
+ const char *count_path, *count_string;
+
+ count_path = GCSPRINTF("%s/usercnt", sshm_path);
+ rc = libxl__xs_read_checked(gc, xt, count_path, &count_string);
+ if (rc || count_string == NULL) goto out;
+ count = atoi(count_string);
+
+ count_string = GCSPRINTF("%d", count+1);
+ rc = libxl__xs_write_checked(gc, xt, count_path, count_string);
+ if (rc) goto out;
+
+ rc = 0;
+out:
+ return rc;
+}
+
+static int libxl__sshm_add_borrower(libxl__gc *gc, uint32_t domid,
+ libxl_static_shm *sshm)
+{
+ int rc, i;
+ const char *sshm_path, *borrower_path;
+ const char *dom_path, *dom_sshm_path, *dom_role_path;
+ const char *xs_value;
+ char *ents[9];
+ libxl_static_shm owner_sshm;
+ uint32_t owner_domid;
+ xen_pfn_t *mapped;
+ unsigned int nmapped = 0;
+ xs_transaction_t xt = XBT_NULL;
+
+ sshm_path = SSHM_PATH(sshm->id);
+ borrower_path = GCSPRINTF("%s/borrowers/%"PRIu32, sshm_path, domid);
+ dom_path = libxl__xs_get_dompath(gc, domid);
+ /* the domain should be in xenstore by now */
+ assert(dom_path);
+ dom_sshm_path = GCSPRINTF("%s/static_shm/%s", dom_path, sshm->id);
+ dom_role_path = GCSPRINTF("%s/role", dom_sshm_path);
+
+ /* prepare the borrower xenstore entries */
+ ents[0] = "begin";
+ ents[1] = GCSPRINTF("0x%"PRIx64, sshm->begin);
+ ents[2] = "size";
+ ents[3] = GCSPRINTF("0x%"PRIx64, sshm->size);
+ ents[4] = "offset";
+ ents[5] = GCSPRINTF("0x%"PRIx64, sshm->offset);
+ ents[6] = "prot";
+ ents[7] = libxl__strdup(gc, libxl_sshm_prot_to_string(sshm->prot));
+ ents[8] = NULL;
+
+ mapped = libxl__calloc(gc, sshm->size >> XC_PAGE_SHIFT, sizeof(xen_pfn_t));
+
+ for (;;) {
+ rc = libxl__xs_transaction_start(gc, &xt);
+ if (rc) goto out;
+
+ if (!libxl__xs_read_checked(gc, xt, sshm_path, &xs_value)) {
+ SSHM_ERROR(domid, sshm->id, "no owner found.");
+ rc = ERROR_FAIL;
+ goto out;
+ }
+
+ /* every ID can appear in each domain at most once */
+ if (libxl__xs_read_checked(gc, xt, dom_sshm_path, &xs_value)) {
+ SSHM_ERROR(domid, sshm->id,
+ "domain tried to map the same ID twice.");
+ rc = ERROR_FAIL;
+ goto out;
+ }
+
+ /* look at the owner info and see if we could do the mapping */
+ rc = libxl__xs_read_checked(gc, xt,
+ GCSPRINTF("%s/prot", sshm_path),
+ &xs_value);
+ if (rc) goto out;
+ libxl_sshm_prot_from_string(xs_value, &owner_sshm.prot);
+
+ rc = libxl__xs_read_checked(gc, xt,
+ GCSPRINTF("%s/begin", sshm_path),
+ &xs_value);
+ if (rc) goto out;
+ owner_sshm.begin = strtoull(xs_value, NULL, 16);
+
+ rc = libxl__xs_read_checked(gc, xt,
+ GCSPRINTF("%s/size", sshm_path),
+ &xs_value);
+ if (rc) goto out;
+ owner_sshm.size = strtoull(xs_value, NULL, 16);
+
+ rc = libxl__xs_read_checked(gc, xt,
+ GCSPRINTF("%s/owner", sshm_path),
+ &xs_value);
+ if (rc) goto out;
+ owner_domid = strtoull(xs_value, NULL, 16);
+
+ if (sshm->prot == LIBXL_SSHM_PROT_UNKNOWN)
+ sshm->prot = owner_sshm.prot;
+
+ /* check if the borrower is asking too much permission */
+ if (owner_sshm.prot < sshm->prot) {
+ SSHM_ERROR(domid, sshm->id, "borrower is asking too much
permission.");
+ rc = ERROR_INVAL;
+ goto out;
+ }
+
+ /* write the result to xenstore and commit */
+ rc = libxl__xs_write_checked(gc, xt, dom_role_path, "borrower");
+ if (rc) goto out;
+ rc = libxl__xs_writev(gc, xt, borrower_path, ents);
+ if (rc) goto out;
+ rc = libxl__sshm_incref(gc, xt, sshm_path);
+ if (rc) goto out;
+
+ rc = libxl__xs_transaction_commit(gc, &xt);
+ if (!rc) break;
+ if (rc < 0) goto out;
+ }
+
+ rc = libxl__sshm_do_map(gc, owner_domid, domid,
+ sshm, &owner_sshm,
+ mapped, &nmapped);
+
+out:
+ if (rc) {
+ /* roll back successfully mapped pages */
+ SSHM_ERROR(domid, sshm->id, "failed to map some pages, cancelling.");
+ for (i = 0; i < nmapped; i++) {
+ xc_domain_remove_from_physmap(CTX->xch, domid, mapped[i]);
+ }
+ }
+
+ libxl__xs_transaction_abort(gc, &xt);
+
+ return rc;
+}
+
+static int libxl__sshm_add_owner(libxl__gc *gc, uint32_t domid,
+ libxl_static_shm *sshm)
+{
+ int rc;
+ const char *sshm_path, *dom_path, *dom_role_path;
+ const char *xs_value;
+ char *ents[13];
+ struct xs_permissions noperm;
+ xs_transaction_t xt = XBT_NULL;
+
+ sshm_path = SSHM_PATH(sshm->id);
+ dom_path = libxl__xs_get_dompath(gc, domid);
+ /* the domain should be in xenstore by now */
+ assert(dom_path);
+ dom_role_path = GCSPRINTF("%s/static_shm/%s/role", dom_path, sshm->id);
+
+ /* prepare the xenstore entries */
+ ents[0] = "owner";
+ ents[1] = GCSPRINTF("%"PRIu32, domid);
+ ents[2] = "begin";
+ ents[3] = GCSPRINTF("0x%"PRIx64, sshm->begin);
+ ents[4] = "size";
+ ents[5] = GCSPRINTF("0x%"PRIx64, sshm->size);
+ ents[6] = "prot";
+ ents[7] = libxl__strdup(gc,
+ libxl_sshm_prot_to_string(sshm->prot));
+ ents[8] = "cache_policy";
+ ents[9] = libxl__strdup(gc,
+ libxl_sshm_cachepolicy_to_string(sshm->cache_policy));
+ ents[10] = "usercnt";
+ ents[11] = "1";
+ ents[12] = NULL;
+
+ /* could only be accessed by Dom0 */
+ noperm.id = 0;
+ noperm.perms = XS_PERM_NONE;
+
+ for (;;) {
+ rc = libxl__xs_transaction_start(gc, &xt);
+ if (rc) goto out;
+
+ if (!libxl__xs_read_checked(gc, xt, sshm_path, &xs_value)) {
+ /* every ID can appear in each domain at most once */
+ if (libxl__xs_read_checked(gc, xt, dom_role_path, &xs_value)) {
+ SSHM_ERROR(domid, sshm->id,
+ "domain tried to map the same ID twice.");
+ rc = ERROR_FAIL;
+ goto out;
+ }
+ rc = libxl__xs_write_checked(gc, xt, dom_role_path, "owner");
+ if (rc) goto out;;
+
+ libxl__xs_mknod(gc, xt, sshm_path, &noperm, 1);
+ libxl__xs_writev(gc, xt, sshm_path, ents);
+ } else {
+ SSHM_ERROR(domid, sshm->id, "can only have one owner.");
+ rc = ERROR_FAIL;
+ goto out;
+ }
+
+ rc = libxl__xs_transaction_commit(gc, &xt);
+ if (!rc) break;
+ if (rc < 0) goto out;
+ }
+
+ rc = 0;
+out:
+ libxl__xs_transaction_abort(gc, &xt);
+ return rc;
+}
+
+int libxl__sshm_add(libxl__gc *gc, uint32_t domid,
+ libxl_static_shm *sshms, int len)
+{
+ int rc, i;
+
+ for (i = 0; i < len; ++i) {
+ if (sshms[i].role == LIBXL_SSHM_ROLE_BORROWER) {
+ rc = libxl__sshm_add_borrower(gc, domid, sshms+i);
+ } else {
+ rc = libxl__sshm_add_owner(gc, domid, sshms+i);
+ }
+ if (rc) return rc;
+ }
+
+ return 0;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/tools/libxl/libxl_x86.c b/tools/libxl/libxl_x86.c
index 8b6759c..dc8c703 100644
--- a/tools/libxl/libxl_x86.c
+++ b/tools/libxl/libxl_x86.c
@@ -619,6 +619,25 @@ void libxl__arch_domain_build_info_setdefault(libxl__gc
*gc,
libxl_defbool_setdefault(&b_info->acpi, true);
}
+bool libxl__arch_domain_support_sshm(const libxl_domain_build_info *b_info)
+{
+ /* This as unsupported for calling p2m_add_foreign on two
+ * DomU's is currently not allowd on x86, see the comments in
+ * x86/mm/p2m.c: p2m_add_foreign.
+ */
+ return false;
+}
+
+int libxl__arch_domain_sshm_cachepolicy_setdefault(libxl_static_shm *sshm)
+{
+ if (sshm->cache_policy == LIBXL_SSHM_CACHEPOLICY_UNKNOWN)
+ sshm->cache_policy = LIBXL_SSHM_CACHEPOLICY_X86_NORMAL;
+ if (sshm->cache_policy < LIBXL_SSHM_CACHEPOLICY_X86_NORMAL)
+ return ERROR_INVAL;
+
+ return 0;
+}
+
/*
* Local variables:
* mode: C
--
1.9.1
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