arm64: VM/PMAP changes for CCA guest support
ClosedPublic
Actions

Authored by sarah.walker2_arm.com on Apr 23 2026, 10:30 AM.

Details

Reviewers

andrew
manu
alc
markj
kib

Commits

rG56abdbc5f709: arm64: VM/PMAP changes for CCA guest support

Summary

When in a realm:

Mappings with mode VM_MEMATTR_DEVICE and VM_MEMATTR_DEVICE_NP are unprotected
Imported busdma buffers in protected memory are always bounced
If EARLY_PRINTK is in use, the UART physical address must be in the unprotected address space

Diff Detail

Repository

rG FreeBSD src repository

Lint

Lint Skipped

Unit

Tests Skipped

Build Status

Buildable 72488
Build 69371: arc lint + arc unit

Event Timeline

sarah.walker2_arm.com created this revision.Apr 23 2026, 10:30 AM

Herald added a reviewer: andrew. · View Herald TranscriptApr 23 2026, 10:30 AM

Herald added a reviewer: andrew. · View Herald Transcript

Herald added a reviewer: manu. · View Herald Transcript

Herald added subscribers: emaste, imp. · View Herald Transcript

sarah.walker2_arm.com requested review of this revision.Apr 23 2026, 10:30 AM

Harbormaster completed remote builds in B72465: Diff 176244.Apr 23 2026, 10:30 AM

sarah.walker2_arm.com added a parent revision: D56598: arm64: Add RSI detection for CCA.Apr 23 2026, 10:30 AM

sarah.walker2_arm.com added a child revision: D56600: arm64: Load SOCDEV_PA as a literal rather than an immediate.

sarah.walker2_arm.com mentioned this in D56520: arm64: Add CCA guest support.Apr 23 2026, 10:31 AM

andrew added reviewers: alc, markj, kib.Apr 23 2026, 3:49 PM

andrew added inline comments.

sys/arm64/arm64/efirt_machdep.c
233	Needs to be on `pa` not page table entry
sys/arm64/arm64/pmap.c
4223
5440–5441	This should be applied to `pa` as it may be wrong under FEAT_LPA2
5761	Is this correct when entering a large page, e.g. when `psind == 2` a level 2 block will be created

Address review comments

Harbormaster completed remote builds in B72488: Diff 176274.Apr 23 2026, 5:26 PM

andrew accepted this revision.May 5 2026, 2:02 PM

This revision is now accepted and ready to land.May 5 2026, 2:02 PM

Closed by commit rG56abdbc5f709: arm64: VM/PMAP changes for CCA guest support (authored by sarah.walker2_arm.com, committed by andrew). · Explain WhyMay 12 2026, 4:56 PM

This revision was automatically updated to reflect the committed changes.

andrew added a commit: rG56abdbc5f709: arm64: VM/PMAP changes for CCA guest support.

I recently updated my Microsoft Dev Kit, and because of this change I'm seeing:

bus_dmamem_alloc failed to align memory properly.

The warning stems from an allocation by the nvme driver:

KDB: stack backtrace:
db_trace_self() at db_trace_self
db_trace_self_wrapper() at db_trace_self_wrapper+0x44
bounce_bus_dmamem_alloc() at bounce_bus_dmamem_alloc+0x258
nvme_ctrlr_start() at nvme_ctrlr_start+0xbc8
nvme_ctrlr_start_config_hook() at nvme_ctrlr_start_config_hook+0x5ec
run_interrupt_driven_config_hooks() at run_interrupt_driven_config_hooks+0x94
boot_run_interrupt_driven_config_hooks() at boot_run_interrupt_driven_config_hooks+0x30
mi_startup() at mi_startup+0x1ec
virtdone() at virtdone+0x70

An added printf reports:

vaddr: 0xffffa000847d3f40, paddr: 1047d3f40, alignment: 1000

In this case, the misalignment appears to be harmless because page size alignment isn't actually needed.

In D56599#1364175, @alc wrote:
I recently updated my Microsoft Dev Kit, and because of this change I'm seeing:
bus_dmamem_alloc failed to align memory properly.

Could you test https://reviews.freebsd.org/D59476 please?

jtranoleary_google.com mentioned this in D60384: gve: align dma buffers to requested boundary.Tue, Oct 6, 9:29 PM