Re: [PATCH v2 1/6] Add an "info pg" command that prints the current page tables

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 31/5/24 16:11, Dr. David Alan Gilbert wrote:
> * Don Porter (porter@cs.unc.edu) wrote:
>> The new "info pg" monitor command prints the current page table,
>> including virtual address ranges, flag bits, and snippets of physical
>> page numbers.  Completely filled regions of the page table with
>> compatible flags are "folded", with the result that the complete
>> output for a freshly booted x86-64 Linux VM can fit in a single
>> terminal window.  The output looks like this:
>>
>> VPN range             Entry         Flags            Physical page
>> [7f0000000-7f0000000] PML4[0fe]     ---DA--UWP
>>    [7f28c0000-7f28fffff]  PDP[0a3]     ---DA--UWP
>>      [7f28c4600-7f28c47ff]  PDE[023]     ---DA--UWP
>>        [7f28c4655-7f28c4656]  PTE[055-056] X--D---U-P 0000007f14-0000007f15
>>        [7f28c465b-7f28c465b]  PTE[05b]     ----A--U-P 0000001cfc
>> ...
>> [ff8000000-ff8000000] PML4[1ff]     ---DA--UWP
>>    [ffff80000-ffffbffff]  PDP[1fe]     ---DA---WP
>>      [ffff81000-ffff81dff]  PDE[008-00e] -GSDA---WP 0000001000-0000001dff
>>    [ffffc0000-fffffffff]  PDP[1ff]     ---DA--UWP
>>      [ffffff400-ffffff5ff]  PDE[1fa]     ---DA--UWP
>>        [ffffff5fb-ffffff5fc]  PTE[1fb-1fc] XG-DACT-WP 00000fec00 00000fee00
>>      [ffffff600-ffffff7ff]  PDE[1fb]     ---DA--UWP
>>        [ffffff600-ffffff600]  PTE[000]     -G-DA--U-P 0000001467
>>
>> This draws heavy inspiration from Austin Clements' original patch.
>>
>> This also adds a generic page table walker, which other monitor
>> and execution commands will be migrated to in subsequent patches.
>>
>> Signed-off-by: Don Porter <porter@cs.unc.edu>
>> ---
>>   hmp-commands-info.hx              |  26 ++
>>   include/monitor/hmp-target.h      |   1 +
>>   target/i386/arch_memory_mapping.c | 486 +++++++++++++++++++++++++++++-
>>   target/i386/cpu.h                 |  16 +
>>   target/i386/monitor.c             | 380 +++++++++++++++++++++++
>>   5 files changed, 908 insertions(+), 1 deletion(-)
>>
>> diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
>> index 20a9835ea8..918b82015c 100644
>> --- a/hmp-commands-info.hx
>> +++ b/hmp-commands-info.hx
>> @@ -237,6 +237,32 @@ ERST
>>           .cmd        = hmp_info_mtree,
>>       },
>>   
>> +#if defined(TARGET_I386)

FYI in order to unify all QEMU system binaries as a single
one, we are trying to remove target-specific bits in monitor.

How 'info pg' should work in a binary supporting heterogeneous
emulation?

>> +    {
>> +        .name       = "pg",
>> +        .args_type  = "",
>> +        .params     = "",
>> +        .help       = "show the page table",
>> +        .cmd        = hmp_info_pg,
>> +    },
>> +#endif
> 
> So that looks OK