On 1/2/24 02:57, Richard Henderson wrote:
> Changes for v3:
> * Rebase.
>
> Blurb from v1:
>
> While working on mmap issues for 8.1, I noticed a lot of corner
> cases of host != guest page size that we implement poorly.
> This seems to be particularly visible on Apple M1 with 16k pages,
> more so than Power with 64k pages for some reason.
>
> Objective 1 is to deprecate and (essentially) disable the -p option.
>
> The effect of -p is apparently confusing, so much so that our own
> testsuite misuses it. One cannot really change the host page size,
> and pretending otherwise means that we don't treat the host memory
> system correctly, and stuff breaks.
>
> I have not yet done the same work for bsd-user.
>
> Objective 2 is to allow the guest page size to change to match the host.
>
> There are corner cases of host != guest page size will fail in odd ways.
> For case of host > guest page size, the issues could be solved with
> softmmu, allowing a non-linear mapping between host and guest addresses
> and also disconnecting host and guest page permissions.
>
> However, host < guest page has issues with SIGBUS which I believe to be
> totally unfixable. At minimum one would need to monitor changes to all
> files mapped in the address space, but I'm sure there is much more.
>
> But as always the best behaviour is obtained when the host and guest
> page sizes match -- there are no corner cases to contend with.
>
> There are a set of guests which can be configured to use multiple page
> sizes, and therefore software developed for those guests (usually) does
> not hard-code a particular page size. For those, we can allow the
> page size to vary and let the guest match the host.
>
> I have only changed aarch64, alpha and ppc guests so far, as those
> are both easy to test and, especially for the case of alpha's default
> 8k page size, prone to failure.
I did some basic testing (built, installed, started chroots) for various
targets and did not see any obvious issues.
I did not specifically checked for particular page sizes though.
Anyway, for the series:
Acked-by: Helge Deller <deller@gmx.de>
Helge
>
>
> r~
>
>
> Richard Henderson (33):
> accel/tcg: Remove qemu_host_page_size from page_protect/page_unprotect
> linux-user: Adjust SVr4 NULL page mapping
> linux-user: Remove qemu_host_page_{size,mask} in probe_guest_base
> linux-user: Remove qemu_host_page_size from create_elf_tables
> linux-user/hppa: Simplify init_guest_commpage
> linux-user/nios2: Remove qemu_host_page_size from init_guest_commpage
> linux-user/arm: Remove qemu_host_page_size from init_guest_commpage
> linux-user: Remove qemu_host_page_{size,mask} from mmap.c
> linux-user: Remove REAL_HOST_PAGE_ALIGN from mmap.c
> linux-user: Remove HOST_PAGE_ALIGN from mmap.c
> migration: Remove qemu_host_page_size
> hw/tpm: Remove HOST_PAGE_ALIGN from tpm_ppi_init
> softmmu/physmem: Remove qemu_host_page_size
> softmmu/physmem: Remove HOST_PAGE_ALIGN
> linux-user: Remove qemu_host_page_size from main
> linux-user: Split out target_mmap__locked
> linux-user: Move some mmap checks outside the lock
> linux-user: Fix sub-host-page mmap
> linux-user: Split out mmap_end
> linux-user: Do early mmap placement only for reserved_va
> linux-user: Split out mmap_h_eq_g
> linux-user: Split out mmap_h_lt_g
> linux-user: Split out mmap_h_gt_g
> tests/tcg: Remove run-test-mmap-*
> tests/tcg: Extend file in linux-madvise.c
> *-user: Deprecate and disable -p pagesize
> cpu: Remove page_size_init
> accel/tcg: Disconnect TargetPageDataNode from page size
> linux-user: Allow TARGET_PAGE_BITS_VARY
> target/arm: Enable TARGET_PAGE_BITS_VARY for AArch64 user-only
> linux-user: Bound mmap_min_addr by host page size
> target/ppc: Enable TARGET_PAGE_BITS_VARY for user-only
> target/alpha: Enable TARGET_PAGE_BITS_VARY for user-only
>
> docs/about/deprecated.rst | 7 +
> docs/user/main.rst | 3 -
> bsd-user/qemu.h | 7 +
> include/exec/cpu-common.h | 7 -
> include/hw/core/cpu.h | 2 -
> target/alpha/cpu-param.h | 16 +-
> target/arm/cpu-param.h | 6 +-
> target/ppc/cpu-param.h | 9 +-
> accel/tcg/translate-all.c | 1 -
> accel/tcg/user-exec.c | 31 +-
> bsd-user/main.c | 21 +-
> cpu-target.c | 13 -
> hw/tpm/tpm_ppi.c | 3 +-
> linux-user/elfload.c | 67 +-
> linux-user/main.c | 33 +-
> linux-user/mmap.c | 714 +++++++++++++---------
> migration/ram.c | 22 +-
> system/physmem.c | 17 +-
> system/vl.c | 1 -
> target/arm/cpu.c | 51 +-
> tests/tcg/multiarch/linux/linux-madvise.c | 2 +
> tests/tcg/alpha/Makefile.target | 3 -
> tests/tcg/arm/Makefile.target | 3 -
> tests/tcg/hppa/Makefile.target | 3 -
> tests/tcg/i386/Makefile.target | 3 -
> tests/tcg/m68k/Makefile.target | 3 -
> tests/tcg/multiarch/Makefile.target | 9 -
> tests/tcg/ppc/Makefile.target | 12 -
> tests/tcg/sh4/Makefile.target | 3 -
> tests/tcg/sparc64/Makefile.target | 6 -
> 30 files changed, 626 insertions(+), 452 deletions(-)
> delete mode 100644 tests/tcg/ppc/Makefile.target
> delete mode 100644 tests/tcg/sparc64/Makefile.target
>