[v4] Add API for making parts of a MMIO page R/O and use it in XHCI console

[PATCH v4 0/2] Add API for making parts of a MMIO page R/O and use it in XHCI console

Posted by Marek Marczykowski-Górecki 6 months ago

On older systems, XHCI xcap had a layout that no other (interesting) registers
were placed on the same page as the debug capability, so Linux was fine with
making the whole page R/O. But at least on Tiger Lake and Alder Lake, Linux
needs to write to some other registers on the same page too.

Add a generic API for making just parts of an MMIO page R/O and use it to fix
USB3 console with share=yes or share=hwdom options. More details in commit
messages.

Marek Marczykowski-Górecki (2):
  x86/mm: add API for marking only part of a MMIO page read only
  drivers/char: Use sub-page ro API to make just xhci dbc cap RO

 xen/arch/x86/hvm/emulate.c      |   2 +-
 xen/arch/x86/hvm/hvm.c          |   4 +-
 xen/arch/x86/include/asm/mm.h   |  25 +++-
 xen/arch/x86/mm.c               | 273 +++++++++++++++++++++++++++++++++-
 xen/arch/x86/pv/ro-page-fault.c |   6 +-
 xen/drivers/char/xhci-dbc.c     |  36 ++--
 6 files changed, 327 insertions(+), 19 deletions(-)

base-commit: b0082b908391b29b7c4dd5e6c389ebd6481926f8
-- 
git-series 0.9.1

Re: [PATCH v4 0/2] Add API for making parts of a MMIO page R/O and use it in XHCI console

Posted by Marek Marczykowski-Górecki 6 months ago

On Wed, May 22, 2024 at 05:39:02PM +0200, Marek Marczykowski-Górecki wrote:
> On older systems, XHCI xcap had a layout that no other (interesting) registers
> were placed on the same page as the debug capability, so Linux was fine with
> making the whole page R/O. But at least on Tiger Lake and Alder Lake, Linux
> needs to write to some other registers on the same page too.
> 
> Add a generic API for making just parts of an MMIO page R/O and use it to fix
> USB3 console with share=yes or share=hwdom options. More details in commit
> messages.
> 
> Marek Marczykowski-Górecki (2):
>   x86/mm: add API for marking only part of a MMIO page read only
>   drivers/char: Use sub-page ro API to make just xhci dbc cap RO

Does any other x86 maintainer feel comfortable ack-ing this series? Jan
already reviewed 2/2 here (but not 1/2 in this version), but also said
he is not comfortable with letting this in without a second maintainer
approval: https://lore.kernel.org/xen-devel/7655e401-b927-4250-ae63-05361a5ee71d@suse.com/

> 
>  xen/arch/x86/hvm/emulate.c      |   2 +-
>  xen/arch/x86/hvm/hvm.c          |   4 +-
>  xen/arch/x86/include/asm/mm.h   |  25 +++-
>  xen/arch/x86/mm.c               | 273 +++++++++++++++++++++++++++++++++-
>  xen/arch/x86/pv/ro-page-fault.c |   6 +-
>  xen/drivers/char/xhci-dbc.c     |  36 ++--
>  6 files changed, 327 insertions(+), 19 deletions(-)
> 
> base-commit: b0082b908391b29b7c4dd5e6c389ebd6481926f8
> -- 
> git-series 0.9.1

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

Re: [PATCH v4 0/2] Add API for making parts of a MMIO page R/O and use it in XHCI console

Posted by Jan Beulich 6 months ago

On 23.05.2024 16:22, Marek Marczykowski-Górecki wrote:
> On Wed, May 22, 2024 at 05:39:02PM +0200, Marek Marczykowski-Górecki wrote:
>> On older systems, XHCI xcap had a layout that no other (interesting) registers
>> were placed on the same page as the debug capability, so Linux was fine with
>> making the whole page R/O. But at least on Tiger Lake and Alder Lake, Linux
>> needs to write to some other registers on the same page too.
>>
>> Add a generic API for making just parts of an MMIO page R/O and use it to fix
>> USB3 console with share=yes or share=hwdom options. More details in commit
>> messages.
>>
>> Marek Marczykowski-Górecki (2):
>>   x86/mm: add API for marking only part of a MMIO page read only
>>   drivers/char: Use sub-page ro API to make just xhci dbc cap RO
> 
> Does any other x86 maintainer feel comfortable ack-ing this series? Jan
> already reviewed 2/2 here (but not 1/2 in this version),

Which, btw, isn't to mean I'm not going to look at it. But 2/2 was the
lower hanging fruit ...

Jan

> but also said
> he is not comfortable with letting this in without a second maintainer
> approval: https://lore.kernel.org/xen-devel/7655e401-b927-4250-ae63-05361a5ee71d@suse.com/