[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [QEMU][PATCHv2 7/8] xen: add map and unmap callbacks for grant region
On Wed, 25 Oct 2023, Vikram Garhwal wrote: > From: Juergen Gross <jgross@xxxxxxxx> > > Add the callbacks for mapping/unmapping guest memory via grants to the > special grant memory region. > > Signed-off-by: Juergen Gross <jgross@xxxxxxxx> > Signed-off-by: Vikram Garhwal <vikram.garhwal@xxxxxxx> > --- > 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 > + } > + > + 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 >
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