Re: [PATCH] privcmd: MMAPBATCH: Fix error handling/reporting

[Jeremy Fitzhardinge <jeremy@goop.org>]

Ian Campbell wrote:
> On error IOCTL_PRIVCMD_MMAPBATCH is expected to set the top nibble of
> the effected MFN and return 0. Currently it leaves the MFN unmodified
> and returns the number of failures. Therefore:
>
> - reimplement remap_domain_mfn_range() using direct
>   HYPERVISOR_mmu_update() calls and small batches. The xen_set_domain_pte()
>   interface does not report errors and since some failures are
>   expected/normal using the multicall infrastructure is too noisy.
> - return 0 as expected
> - writeback the updated MFN list to mmapbatch->arr not over mmapbatch,
>   smashing the caller's stack.
> - remap_domain_mfn_range can be static.
>
> With this change I am able to start an HVM domain.
>   

This breaks compiling xenfs as a module; neither flush_tlb_all or 
arbitrary_virt_to_machine are exported, I think.

    J