On Wed, Oct 25, 2023 at 06:32:26PM -0700, Stefano Stabellini wrote:
> On Wed, 25 Oct 2023, Vikram Garhwal wrote:
> > From: Juergen Gross <jgr...@suse.com>
> >
> > Add the callbacks for mapping/unmapping guest memory via grants to the
> > special grant memory region.
> >
> > Signed-off-by: Juergen Gross <jgr...@suse.com>
> > Signed-off-by: Vikram Garhwal <vikram.garh...@amd.com>
> > ---
> > hw/xen/xen-mapcache.c | 175 +++++++++++++++++++++++++++++++++++++++++-
> > system/physmem.c | 11 ++-
> > 2 files changed, 181 insertions(+), 5 deletions(-)
> >
> > diff --git a/hw/xen/xen-mapcache.c b/hw/xen/xen-mapcache.c
> > index 8a61c7dde6..feb4a3b886 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>
> >
> > //#define MAPCACHE_DEBUG
> >
> > @@ -385,7 +389,7 @@ 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;
> > @@ -594,10 +598,178 @@ 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) {
> > + return NULL;
>
> missing qemu_mutex_unlock
Oops, thanks for catching this! Will fix it in v3.
>
>
> > + }
> > +
> > + 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));
> > @@ -612,6 +784,7 @@ 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 5db1b32823..155a8c05fb 100644
> > --- a/system/physmem.c
> > +++ b/system/physmem.c
> > @@ -2233,13 +2233,16 @@ 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
> >
