From 4fd5ca829ae28f1f009210ab1cd42f86671015ec Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Mon, 17 Jan 2022 04:12:32 +0000 Subject: [PATCH] libvhost-user: Simplify VHOST_USER_REM_MEM_REG Let's avoid having to manually copy all elements. Copy only the ones necessary to close the hole and perform the operation in-place without a second array. Reviewed-by: Stefan Hajnoczi Signed-off-by: David Hildenbrand Signed-off-by: Raphael Norwitz Message-Id: <20220117041050.19718-4-raphael.norwitz@nutanix.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- subprojects/libvhost-user/libvhost-user.c | 30 +++++++++++------------ 1 file changed, 14 insertions(+), 16 deletions(-) diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/libvhost-user/libvhost-user.c index 1a8fc9d600..7dd8e918b4 100644 --- a/subprojects/libvhost-user/libvhost-user.c +++ b/subprojects/libvhost-user/libvhost-user.c @@ -811,10 +811,8 @@ static inline bool reg_equal(VuDevRegion *vudev_reg, static bool vu_rem_mem_reg(VuDev *dev, VhostUserMsg *vmsg) { - int i, j; - bool found = false; - VuDevRegion shadow_regions[VHOST_USER_MAX_RAM_SLOTS] = {}; VhostUserMemoryRegion m = vmsg->payload.memreg.region, *msg_region = &m; + int i; if (vmsg->fd_num != 1) { vmsg_close_fds(vmsg); @@ -841,28 +839,28 @@ vu_rem_mem_reg(VuDev *dev, VhostUserMsg *vmsg) { DPRINT(" mmap_offset 0x%016"PRIx64"\n", msg_region->mmap_offset); - for (i = 0, j = 0; i < dev->nregions; i++) { - if (!reg_equal(&dev->regions[i], msg_region)) { - shadow_regions[j].gpa = dev->regions[i].gpa; - shadow_regions[j].size = dev->regions[i].size; - shadow_regions[j].qva = dev->regions[i].qva; - shadow_regions[j].mmap_addr = dev->regions[i].mmap_addr; - shadow_regions[j].mmap_offset = dev->regions[i].mmap_offset; - j++; - } else { - found = true; + for (i = 0; i < dev->nregions; i++) { + if (reg_equal(&dev->regions[i], msg_region)) { VuDevRegion *r = &dev->regions[i]; void *m = (void *) (uintptr_t) r->mmap_addr; if (m) { munmap(m, r->size + r->mmap_offset); } + + break; } } - if (found) { - memcpy(dev->regions, shadow_regions, - sizeof(VuDevRegion) * VHOST_USER_MAX_RAM_SLOTS); + if (i < dev->nregions) { + /* + * Shift all affected entries by 1 to close the hole at index i and + * zero out the last entry. + */ + memmove(dev->regions + i, dev->regions + i + 1, + sizeof(VuDevRegion) * (dev->nregions - i - 1)); + memset(dev->regions + dev->nregions - 1, 0, + sizeof(VuDevRegion)); DPRINT("Successfully removed a region\n"); dev->nregions--; vmsg_set_reply_u64(vmsg, 0);