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vm-virtio: Fix FS_IO callback for virtio-fs

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FS_IO is part of the actions a vhost-user-fs daemon can ask the VMM to
perform on its behalf. It is meant to read/write the content from a file
descriptor directly into a guest memory region. This region can either
be a RAM region or the dedicated cache region for virtio-fs.

The way FS_IO was implemented, it was only expecting the guest physical
address provided through the "cache_offset" field to refer to the cache
region. Unfortunately, this was only implementing FS_IO partially.

This patch extends the existing FS_IO implementation by checking the GPA
against the cache region as a first step, but if it is not part of the
cache region address range, then we fallback onto searching for a RAM
region that could match. If there is a matching RAM region, we retrieve
the corresponding host address to let the VMM read/write from/to it.

Fixes: #1054

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Jose Carlos Venegas Munoz <jose.carlos.venegas.munoz@intel.com>
This commit is contained in:
Jose Carlos Venegas Munoz 2020-04-22 23:10:31 +00:00 committed by Rob Bradford
parent df14a68e87
commit 3eaeba4b55
1 changed files with 28 additions and 12 deletions
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24
vm-virtio/src/vhost_user/fs.rs
View File

@ -27,8 +27,8 @@ use vhost_rs::vhost_user::{
};
use vhost_rs::VhostBackend;
use vm_memory::{
Address, ByteValued, GuestAddress, GuestAddressSpace, GuestMemoryAtomic, GuestMemoryMmap,
MmapRegion,
Address, ByteValued, GuestAddress, GuestAddressSpace, GuestMemory, GuestMemoryAtomic,
GuestMemoryMmap, MmapRegion,
};
use vm_migration::{Migratable, MigratableError, Pausable, Snapshottable, Transportable};
use vmm_sys_util::eventfd::EventFd;
@ -39,6 +39,7 @@ struct SlaveReqHandler {
cache_offset: GuestAddress,
cache_size: u64,
mmap_cache_addr: u64,
mem: GuestMemoryAtomic<GuestMemoryMmap>,
}
impl SlaveReqHandler {
@ -183,6 +184,7 @@ impl VhostUserMasterReqHandler for SlaveReqHandler {
let cache_end = self.cache_offset.raw_value() + self.cache_size;
let efault = libc::EFAULT;
let mut ptr = if gpa >= self.cache_offset.raw_value() && gpa < cache_end {
let offset = gpa
.checked_sub(self.cache_offset.raw_value())
.ok_or_else(|| io::Error::from_raw_os_error(efault))?;
@ -190,11 +192,24 @@ impl VhostUserMasterReqHandler for SlaveReqHandler {
.checked_add(fs.len[i])
.ok_or_else(|| io::Error::from_raw_os_error(efault))?;
if gpa < self.cache_offset.raw_value() || gpa >= cache_end || end >= cache_end {
if end >= cache_end {
return Err(io::Error::from_raw_os_error(efault));
}
let mut ptr = self.mmap_cache_addr + offset;
self.mmap_cache_addr + offset
} else {
self.mem
.memory()
.get_host_address(GuestAddress(gpa))
.map_err(|e| {
error!(
"Failed to find RAM region associated with guest physical address 0x{:x}: {:?}",
gpa, e
);
io::Error::from_raw_os_error(efault)
})? as u64
};
while len > 0 {
let ret = if (fs.flags[i] & VhostUserFSSlaveMsgFlags::MAP_W)
== VhostUserFSSlaveMsgFlags::MAP_W
@ -479,6 +494,7 @@ impl VirtioDevice for Fs {
cache_offset: cache.0.addr,
cache_size: cache.0.len,
mmap_cache_addr: cache.0.host_addr,
mem,
}));
let req_handler = MasterReqHandler::new(vu_master_req_handler).map_err(|e| {