For nonroot vfio-pci device, its prefetchable bars will be allocated
in continuous region, its nonprefetchable bars will be allocated in
another continuous region. Without descending the bar's size, this
allocation waste some mmio.
For example, a vfio-pci device has two non prefetchable bars:
bar0's size is 1M, bar2's size is 8M.
without descending [bar0, bar2], it will allocate 16M mmio, 0~8M
for Bar0, 8~16M for Bar2, although bar0 need 1M only, it occupy 8M
to satisfy bar2's 8M alignment requirement.
With descending [bar2, bar0], it will allocate 9M mmio, 0~8M for
bar2, 8M ~ 9M for bar0.
BUG=b:185084350
TEST=check pcie rp's bridge window in brya-manatee.
Change-Id: I7d93e601f6a46cabe8896aaec065a9dba18c60fa
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3500060
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Daniel Verkamp <dverkamp@chromium.org>
crosvm is a virtual machine monitor (VMM) based on Linux’s KVM hypervisor, with a focus on
simplicity, security, and speed. crosvm is intended to run Linux guests, originally as a security
boundary for running native applications on the Chrome OS platform. Compared to QEMU, crosvm doesn’t
emulate architectures or real hardware, instead concentrating on paravirtualized devices, such as
the virtio standard.
crosvm is currently used to run Linux/Android guests on Chrome OS devices.
For contribution, see
the contributor guide. Mirror repository is
available at GitHub for your convenience, but we don't
accept bug reports or pull requests there.
9a24be33e9
