Mailing List Archive

From: Juergen Gross <jgross@suse.com>

Add the callbacks for mapping/unmapping guest memory via grants to the
special grant memory region.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Vikram Garhwal <vikram.garhwal@amd.com>
---
hw/xen/xen-mapcache.c | 176 +++++++++++++++++++++++++++++++++++++++++-
system/physmem.c | 11 ++-
2 files changed, 182 insertions(+), 5 deletions(-)

diff --git a/hw/xen/xen-mapcache.c b/hw/xen/xen-mapcache.c
index 179b7e95b2..2e4c9b4947 100644
--- a/hw/xen/xen-mapcache.c
+++ b/hw/xen/xen-mapcache.c
@@ -9,6 +9,8 @@
*/

#include "qemu/osdep.h"
+#include "qemu/queue.h"
+#include "qemu/thread.h"
#include "qemu/units.h"
#include "qemu/error-report.h"

@@ -23,6 +25,8 @@
#include "sysemu/xen-mapcache.h"
#include "trace.h"

+#include <xenevtchn.h>
+#include <xengnttab.h>

#if HOST_LONG_BITS == 32
# define MCACHE_BUCKET_SHIFT 16
@@ -377,7 +381,7 @@ uint8_t *xen_map_cache(hwaddr phys_addr, hwaddr size,
return p;
}

-ram_addr_t xen_ram_addr_from_mapcache(void *ptr)
+static ram_addr_t xen_ram_addr_from_mapcache_try(void *ptr)
{
MapCacheEntry *entry = NULL;
MapCacheRev *reventry;
@@ -588,10 +592,179 @@ uint8_t *xen_replace_cache_entry(hwaddr old_phys_addr,
return p;
}

+struct XENMappedGrantRegion {
+ void *addr;
+ unsigned int pages;
+ unsigned int refs;
+ unsigned int prot;
+ uint32_t idx;
+ QLIST_ENTRY(XENMappedGrantRegion) list;
+};
+
+static xengnttab_handle *xen_region_gnttabdev;
+static QLIST_HEAD(GrantRegionList, XENMappedGrantRegion) xen_grant_mappings =
+ QLIST_HEAD_INITIALIZER(xen_grant_mappings);
+static QemuMutex xen_map_mutex;
+
+static void *xen_map_grant_dyn(MemoryRegion **mr, hwaddr addr, hwaddr *plen,
+ bool is_write, MemTxAttrs attrs)
+{
+ unsigned int page_off = addr & (XC_PAGE_SIZE - 1);
+ unsigned int i;
+ unsigned int total_grants = 0;
+ unsigned int nrefs = (page_off + *plen + XC_PAGE_SIZE - 1) >> XC_PAGE_SHIFT;
+ uint32_t ref = (addr - XEN_GRANT_ADDR_OFF) >> XC_PAGE_SHIFT;
+ uint32_t *refs = NULL;
+ unsigned int prot = PROT_READ;
+ struct XENMappedGrantRegion *mgr = NULL;
+
+ if (is_write) {
+ prot |= PROT_WRITE;
+ }
+
+ qemu_mutex_lock(&xen_map_mutex);
+
+ QLIST_FOREACH(mgr, &xen_grant_mappings, list) {
+ if (mgr->idx == ref &&
+ mgr->pages == nrefs &&
+ (mgr->prot & prot) == prot) {
+ break;
+ }
+
+ total_grants += mgr->pages;
+ }
+
+ if (!mgr) {
+ if (nrefs + total_grants >= XEN_MAX_VIRTIO_GRANTS) {
+ qemu_mutex_unlock(&xen_map_mutex);
+ return NULL;
+ }
+
+ mgr = g_new(struct XENMappedGrantRegion, 1);
+
+ if (nrefs == 1) {
+ refs = &ref;
+ } else {
+ refs = g_new(uint32_t, nrefs);
+ for (i = 0; i < nrefs; i++) {
+ refs[i] = ref + i;
+ }
+ }
+ mgr->addr = xengnttab_map_domain_grant_refs(xen_region_gnttabdev, nrefs,
+ xen_domid, refs, prot);
+ if (mgr->addr) {
+ mgr->pages = nrefs;
+ mgr->refs = 1;
+ mgr->prot = prot;
+ mgr->idx = ref;
+
+ QLIST_INSERT_HEAD(&xen_grant_mappings, mgr, list);
+ } else {
+ g_free(mgr);
+ mgr = NULL;
+ }
+ } else {
+ mgr->refs++;
+ }
+
+ qemu_mutex_unlock(&xen_map_mutex);
+
+ if (nrefs > 1) {
+ g_free(refs);
+ }
+
+ return mgr ? mgr->addr + page_off : NULL;
+}
+
+static void xen_unmap_grant_dyn(MemoryRegion *mr, void *buffer, ram_addr_t addr,
+ hwaddr len, bool is_write, hwaddr access_len)
+{
+ unsigned int page_off = (unsigned long)buffer & (XC_PAGE_SIZE - 1);
+ unsigned int nrefs = (page_off + len + XC_PAGE_SIZE - 1) >> XC_PAGE_SHIFT;
+ unsigned int prot = PROT_READ;
+ struct XENMappedGrantRegion *mgr = NULL;
+
+ if (is_write) {
+ prot |= PROT_WRITE;
+ }
+
+ qemu_mutex_lock(&xen_map_mutex);
+
+ QLIST_FOREACH(mgr, &xen_grant_mappings, list) {
+ if (mgr->addr == buffer - page_off &&
+ mgr->pages == nrefs &&
+ (mgr->prot & prot) == prot) {
+ break;
+ }
+ }
+ if (mgr) {
+ mgr->refs--;
+ if (!mgr->refs) {
+ xengnttab_unmap(xen_region_gnttabdev, mgr->addr, nrefs);
+
+ QLIST_REMOVE(mgr, list);
+ g_free(mgr);
+ }
+ } else {
+ error_report("xen_unmap_grant_dyn() trying to unmap unknown buffer");
+ }
+
+ qemu_mutex_unlock(&xen_map_mutex);
+}
+
+static ram_addr_t xen_ram_addr_from_grant_cache(void *ptr)
+{
+ unsigned int page_off = (unsigned long)ptr & (XC_PAGE_SIZE - 1);
+ struct XENMappedGrantRegion *mgr = NULL;
+ ram_addr_t raddr = RAM_ADDR_INVALID;
+
+ qemu_mutex_lock(&xen_map_mutex);
+
+ QLIST_FOREACH(mgr, &xen_grant_mappings, list) {
+ if (mgr->addr == ptr - page_off) {
+ break;
+ }
+ }
+
+ if (mgr) {
+ raddr = (mgr->idx << XC_PAGE_SHIFT) + page_off + XEN_GRANT_ADDR_OFF;
+ }
+
+ qemu_mutex_unlock(&xen_map_mutex);
+
+ return raddr;
+}
+
+ram_addr_t xen_ram_addr_from_mapcache(void *ptr)
+{
+ ram_addr_t raddr;
+
+ raddr = xen_ram_addr_from_mapcache_try(ptr);
+ if (raddr == RAM_ADDR_INVALID) {
+ raddr = xen_ram_addr_from_grant_cache(ptr);
+ }
+
+ return raddr;
+}
+
+static const struct MemoryRegionOps xen_grant_mr_ops = {
+ .map = xen_map_grant_dyn,
+ .unmap = xen_unmap_grant_dyn,
+ .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
MemoryRegion *xen_init_grant_ram(void)
{
RAMBlock *block;

+ qemu_mutex_init(&xen_map_mutex);
+
+ xen_region_gnttabdev = xengnttab_open(NULL, 0);
+ if (xen_region_gnttabdev == NULL) {
+ fprintf(stderr, "can't open gnttab device\n");
+ return NULL;
+ }
+
memory_region_init(&ram_grants, NULL, "xen.grants",
XEN_MAX_VIRTIO_GRANTS * XC_PAGE_SIZE);
block = g_malloc0(sizeof(*block));
@@ -606,6 +779,7 @@ MemoryRegion *xen_init_grant_ram(void)
ram_grants.ram_block = block;
ram_grants.ram = true;
ram_grants.terminates = true;
+ ram_grants.ops = &xen_grant_mr_ops;
ram_block_add_list(block);
memory_region_add_subregion(get_system_memory(), XEN_GRANT_ADDR_OFF,
&ram_grants);
diff --git a/system/physmem.c b/system/physmem.c
index d989e9fc1f..e6fc075d8f 100644
--- a/system/physmem.c
+++ b/system/physmem.c
@@ -2232,13 +2232,16 @@ RAMBlock *qemu_ram_block_from_host(void *ptr, bool round_offset,

if (xen_enabled()) {
ram_addr_t ram_addr;
+
RCU_READ_LOCK_GUARD();
ram_addr = xen_ram_addr_from_mapcache(ptr);
- block = qemu_get_ram_block(ram_addr);
- if (block) {
- *offset = ram_addr - block->offset;
+ if (ram_addr != RAM_ADDR_INVALID) {
+ block = qemu_get_ram_block(ram_addr);
+ if (block) {
+ *offset = ram_addr - block->offset;
+ }
+ return block;
}
- return block;
}

RCU_READ_LOCK_GUARD();
--
2.17.1