On Thu, 24 Mar 2022 at 17:39, <baskov@xxxxxxxxx> wrote: > > On 2022-03-18 19:37, Peter Jones wrote: > > On Thu, Mar 03, 2022 at 08:47:59PM +0000, Matthew Garrett wrote: > >> On Thu, Mar 03, 2022 at 04:42:07PM +0300, baskov@xxxxxxxxx wrote: > >> > On 2022-02-28 21:30, Matthew Garrett wrote: > >> > > On Mon, Feb 28, 2022 at 05:45:53PM +0100, Ard Biesheuvel wrote: > >> > > > >> > > > Given that this is a workaround for a very specific issue arising on > >> > > > PI based implementations of UEFI, I consider this a quirk, and so I > >> > > > think this approach is reasonable. I'd still like to gate it on some > >> > > > kind of identification, though - perhaps something related to DMI like > >> > > > the x86 core kernel does as well. > >> > > > >> > > When the V1 patches were reviewed, you suggested allocating > >> > > EFI_LOADER_CODE rather than EFI_LOADER_DATA. The example given for a > >> > > failure case is when NxMemoryProtectionPolicy is set to 0x7fd4, in which > >> > > case EFI_LOADER_CODE, EFI_BOOT_SERVICES_CODE and > >> > > EFI_RUNTIEM_SERVICES_CODE should not have the nx policy applied. So it > >> > > seems like your initial suggestion (s/LOADER_DATA/LOADER_CODE/) should > >> > > have worked, even if there was disagreement about whether the spec > >> > > required it to. Is this firmware applying a stricter policy? > >> > > >> > Yes, this firmware is being modified to enforce stricter policy. > >> > >> Ok. I think this should really go through the UEFI spec process - I > >> agree that from a strict interpretation of the spec, what this > >> firmware > >> is doing is legitimate, but I don't like having a situation where we > >> have to depend on the DXE spec. > > > > It's in the process of getting into the UEFI spec now as > > https://bugzilla.tianocore.org/show_bug.cgi?id=3519 . > > > >> How does Windows handle this? Just update the page tables itself for > >> any > >> regions it needs during boot? > > > > Microsoft's bootloader sets up its own pagetables, though I believe > > they're switching it to use the (soon to be) standardized API. > > The third version of the patch is the most close in structure > to the proposed protocol. And until the protocol is standardized and > implemented on problematic firmware, I think, it remains the better > solution in terms of simplicity and further porting to the new > protocol. > > It is desirable to get the issue resolved, and make the kernel stricter > comply to the spec, without waiting for the new API implementation. > And later, switch the kernel to be using the protocol with > subsequent patches as soon as it gets usable. > > So, is there a chance for these patches to be accepted in current > form, or with some modifications? > I am fine with taking the v3, as it is the most likely to only affect the systems that actually need this change in behavior. So unless there are any objections, I will queue these up after the merge window.
