xen: arm: improve VMID allocation.

The VMID field is 8 bits. Rather than allowing only up to 256 VMs per host
reboot before things start "acting strange" instead maintain a simple bitmap
of used VMIDs and allocate them statically to guests upon creation.

This limits us to 256 concurrent VMs which is a reasonable improvement.
Eventually we will want a proper scheme to allocate VMIDs on context switch.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index aa87fb1779..62147b21ad 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -548,6 +548,8 @@ void __init start_xen(unsigned long boot_phys_offset,
 
     setup_virt_paging();
 
+    p2m_vmid_allocator_init();
+
     softirq_init();
 
     tasklet_subsys_init();