Commit 875b9fd9 authored by Raphael Norwitz's avatar Raphael Norwitz Committed by Michael S. Tsirkin
Browse files

Support individual region unmap in libvhost-user 



When the VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS protocol feature is
enabled, on memory hot-unplug qemu will transmit memory regions to
remove individually using the new message VHOST_USER_REM_MEM_REG
message. With this change, vhost-user backends build with libvhost-user
can now unmap individual memory regions when receiving the
VHOST_USER_REM_MEM_REG message.

Qemu only sends VHOST_USER_REM_MEM_REG messages when the
VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS feature is negotiated, and
support for that feature has not yet been added in libvhost-user, this
new functionality is not yet used.

Signed-off-by: default avatarRaphael Norwitz <raphael.norwitz@nutanix.com>
Message-Id: <1588533678-23450-10-git-send-email-raphael.norwitz@nutanix.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent ec94c8e6

contrib/libvhost-user/libvhost-user.c

+63 −0
Original line number Diff line number Diff line
@@ -139,6 +139,7 @@ vu_request_to_string(unsigned int req) 
        REQ(VHOST_USER_VRING_KICK),

        REQ(VHOST_USER_GET_MAX_MEM_SLOTS),

        REQ(VHOST_USER_ADD_MEM_REG),

        REQ(VHOST_USER_REM_MEM_REG),

        REQ(VHOST_USER_MAX),

    };

#undef REQ
@@ -763,6 +764,66 @@ vu_add_mem_reg(VuDev *dev, VhostUserMsg *vmsg) { 
    }

}



static inline bool reg_equal(VuDevRegion *vudev_reg,

                             VhostUserMemoryRegion *msg_reg)

{

    if (vudev_reg->gpa == msg_reg->guest_phys_addr &&

        vudev_reg->qva == msg_reg->userspace_addr &&

        vudev_reg->size == msg_reg->memory_size) {

        return true;

    }



    return false;

}



static bool

vu_rem_mem_reg(VuDev *dev, VhostUserMsg *vmsg) {

    int i, j;

    bool found = false;

    VuDevRegion shadow_regions[VHOST_MEMORY_MAX_NREGIONS] = {};

    VhostUserMemoryRegion m = vmsg->payload.memreg.region, *msg_region = &m;



    DPRINT("Removing region:\n");

    DPRINT("    guest_phys_addr: 0x%016"PRIx64"\n",

           msg_region->guest_phys_addr);

    DPRINT("    memory_size:     0x%016"PRIx64"\n",

           msg_region->memory_size);

    DPRINT("    userspace_addr   0x%016"PRIx64"\n",

           msg_region->userspace_addr);

    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_offset = dev->regions[i].mmap_offset;

            j++;

        } else {

            found = true;

            VuDevRegion *r = &dev->regions[i];

            void *m = (void *) (uintptr_t) r->mmap_addr;



            if (m) {

                munmap(m, r->size + r->mmap_offset);

            }

        }

    }



    if (found) {

        memcpy(dev->regions, shadow_regions,

               sizeof(VuDevRegion) * VHOST_MEMORY_MAX_NREGIONS);

        DPRINT("Successfully removed a region\n");

        dev->nregions--;

        vmsg_set_reply_u64(vmsg, 0);

    } else {

        vu_panic(dev, "Specified region not found\n");

    }



    return true;

}



static bool

vu_set_mem_table_exec_postcopy(VuDev *dev, VhostUserMsg *vmsg)

{
@@ -1771,6 +1832,8 @@ vu_process_message(VuDev *dev, VhostUserMsg *vmsg) 
        return vu_handle_get_max_memslots(dev, vmsg);

    case VHOST_USER_ADD_MEM_REG:

        return vu_add_mem_reg(dev, vmsg);

    case VHOST_USER_REM_MEM_REG:

        return vu_rem_mem_reg(dev, vmsg);

    default:

        vmsg_close_fds(vmsg);

        vu_panic(dev, "Unhandled request: %d", vmsg->request);

contrib/libvhost-user/libvhost-user.h

+1 −0
Original line number Diff line number Diff line
@@ -99,6 +99,7 @@ typedef enum VhostUserRequest { 
    VHOST_USER_VRING_KICK = 35,

    VHOST_USER_GET_MAX_MEM_SLOTS = 36,

    VHOST_USER_ADD_MEM_REG = 37,

    VHOST_USER_REM_MEM_REG = 38,

    VHOST_USER_MAX

} VhostUserRequest;