Re: [PATCHv5 06/12] x86/boot/compressed: Handle unaccepted memory
From: Gupta, Pankaj
Date: Wed Jun 01 2022 - 11:49:39 EST
Hi y'all, I've made minimal changes to OVMF to prevalidate only up to
4GB and leave the rest unaccepted, as Thomas Lendacky recommended
https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FAMDESE%2Fovmf%2Fpull%2F4%23issuecomment-1138606275&data=05%7C01%7Cpankaj.gupta%40amd.com%7Cde8fd09ad93f4420bd7408da43568f68%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637896336342540814%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=K93%2F1FrPOo4bIWcssHoisM8vDkOBjWh69bUWosT%2Bt0E%3D&reserved=0 and ran
a memtouch test to see if this change behaves as expected. One thing
that struck me is that an 8GB machine reports 2044MB free with this
change (free -k) whereas without it, I see 7089MB free. I think that
unaccepted memory should be classified as free in meminfo, no? I'm not
familiar enough with that code to say what specific change needs to be
made.
Is it memory accounting issue when accepting all the memory at boot time
compared to 4GB:4GB preboot_acceptance:use_time_acceptance split?
You said you ran memtouch (don't know how it works, assuming it uses
memory)? Doesn't that mean most of the memory used and hence accepted?
So, free memory reduced?
Just trying to understand the issue.
Thanks,
Pankaj
On Sun, May 15, 2022 at 11:47 PM Xu, Min M <min.m.xu@xxxxxxxxx> wrote:
On May 13, 2022 10:45 PM, Kirill A. Shutemov wrote:
On Fri, May 13, 2022 at 11:01:43AM +0200, Borislav Petkov wrote:
+ mroth
- brijesh
On Thu, May 12, 2022 at 10:34:02PM -0700, Dionna Amalie Glaze wrote:
Kirill, I've been tracking these changes to see if we can handle the
unaccepted memory type for SEV-SNP, but testing has been an issue.
The proposed patch in Ovmf to introduce unaccepted memory seems to
have stalled out last September
(https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.mail-archive.com%2Fdevel%40edk2.groups.io%2Fmsg35842.html&data=05%7C01%7Cpankaj.gupta%40amd.com%7Cde8fd09ad93f4420bd7408da43568f68%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637896336342540814%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=Hku8nQJGOg%2FdQqypHxw2eLFG0e%2FE6HoF5VXSIhMpmx0%3D&reserved=0)
and is particularly difficult to adapt to SEV-SNP since it doesn't
follow the TDVF way of initializing all memory. Is there a different
development I might have missed so that we might test these cases?
Without the UEFI introducing EFI_UNACCEPTED_MEMORY type, any
kernel
uses are essentially dead code.
+ Min, Jiaqi.
I don't follow firmware development. Min, Jiaqi, could you comment?
We have prepared the patch for unaccepted memory and it is now working in our internal release.
But there is an obstacle to upstream it to edk2 master branch.
The patch-set depends on the definition of UEFI_RESOURCE_MEMORY_UNACCEPTED in PI spec. This is proposed in https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fmicrosoft%2Fmu_basecore%2Fpull%2F66%2Ffiles%23diff-b20a11152d1ce9249c691be5690b4baf52069efadf2e2546cdd2eb663d80c9e4R237&data=05%7C01%7Cpankaj.gupta%40amd.com%7Cde8fd09ad93f4420bd7408da43568f68%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637896336342540814%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=v7s68GZWXJfaXB7vfvXjAlTD2KLOSghk%2Bj3GXF3FTVg%3D&reserved=0, according to UEFI-Code-First. The proposal was approved in 2021 in UEFI Mantis, and will be added to the new PI.next specification. (Till now it has not been added in the latest PI spec.)
So UEFI_RESOURCE_MEMORY_UNACCEPTED cannot be added in MdePkg which make it difficult to submit the patch to edk2 community for review. See this link: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fedk2.groups.io%2Fg%2Fdevel%2Fmessage%2F87558&data=05%7C01%7Cpankaj.gupta%40amd.com%7Cde8fd09ad93f4420bd7408da43568f68%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637896336342540814%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=WVIJ2yRRd2URwIF85Dp0WD4ovibZlsobijIGbN6MWZQ%3D&reserved=0
Please be noted: UEFI_RESOURCE_MEMORY_UNACCEPTED (defined in PI spec) is different from EFI_UNACCEPTED_MEMORY (defined in UEFI spec)
I will submit the patch-set once the new definition is added in the new PI.next spec.
Thanks
Min