[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH] exec.c: Allow memory region start_addr and regi
From: |
Avi Kivity |
Subject: |
Re: [Qemu-devel] [PATCH] exec.c: Allow memory region start_addr and region_offset to vary in low bits |
Date: |
Mon, 05 Dec 2011 15:40:35 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:8.0) Gecko/20111115 Thunderbird/8.0 |
On 12/05/2011 01:01 PM, Peter Maydell wrote:
> Fix a long-standing deficiency of cpu_register_physical_memory_log()
> where the start address and region offset had to have the same low
> bits (otherwise the IO functions would be passed an incorrect address
> offset). This was most likely to bite when registering memory regions
> which started at a non-page-boundary.
>
> Signed-off-by: Peter Maydell <address@hidden>
> ---
> This is such a small change to correct this issue that I'm kind of
> suspicious of it :-)
Your instincts are correct, unfortunately.
> @@ -2677,7 +2674,11 @@ void
> cpu_register_physical_memory_log(target_phys_addr_t start_addr,
> if (phys_offset == IO_MEM_UNASSIGNED) {
> region_offset = start_addr;
> }
> - region_offset &= TARGET_PAGE_MASK;
> + /* Adjust the region offset to account for the start_addr possibly
> + * not being page aligned, so we end up passing the IO functions
> + * the true offset from the start of the region.
> + */
> + region_offset -= (start_addr & ~TARGET_PAGE_MASK);
> size = (size + TARGET_PAGE_SIZE - 1) & TARGET_PAGE_MASK;
> end_addr = start_addr + (target_phys_addr_t)size;
>
region_offset is added to iotlb in tlb_set_page(), smashing the low bits
with your change. It's safe in subpage, since that doesn't happen there.
--
error compiling committee.c: too many arguments to function