[Qemu-devel] viewing continuous guest virtual memory as continuous in qemu

[Alon Levy]

Hi,

 I'm trying to acheive the $subject. Some background: currently spice relies on 
a preallocated pci bar for both surfaces and for VGA framebuffer + commands. I 
have been trying to get rid of the surfaces bar. To do that I allocate memory 
in the guest and then translate it for spice-server consumption using 
cpu_physical_memory_map.

 AFAIU this works only when the guest allocates a continuous range of physical 
pages. This is a large requirement from the guest, which I'd like to drop. So I 
would like to have the guest use a regular allocator, generating for instance 
two sequential pages in virtual memory that are scattered in physical memory. 
Those two physical guest page addresses (gp1 and gp2) correspond to two host 
virtual memory addresses (hv1, hv2). I would now like to provide to 
spice-server a single virtual address p that maps to those two pages in 
sequence. I don't want to handle my own scatter-gather list, I would like to 
have this mapping done once so I can use an existing library that requires a 
single pointer (for instance pixman or libGL) to do the rendering.

 Is there any way to acheive that without host kernel support, in user space, 
i.e. in qemu? or with an existing host kernel device?

 I'd appreciate any help,

Alon