x86/tdx: Release private memory before private->shared conversion

[Dexuan Cui (dcui)]

The code is from Intel:
https://lore.kernel.org/all/20260604093551.1511079-6-zhenzhong.duan@intel.com/#t https://lore.kernel.org/all/20260604093551.1511079-7-zhenzhong.duan@intel.com/

I rebased the code to the OHCL branch product/hcl-main/6.18.

[Copilot]

Pull request overview

This PR backports/rebases upstream Intel TDX guest changes to release accepted private pages back to the TDX “PENDING” state before performing private→shared GPA conversion, aiming to reduce failures when converting pages back to private on buggy VMMs.

Changes:

• Add new TDCALL leaf ID and TDCS config flag bit for PAGE.RELEASE support.
• Detect PAGE.RELEASE support at TDX guest setup time.
• Implement TDG.MEM.PAGE.RELEASE flow and invoke it before private→shared conversion in tdx_enc_status_changed_phys().

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
arch/x86/include/asm/shared/tdx.h	Adds constants for TDG.MEM.PAGE.RELEASE leaf ID and TDCS PAGE_RELEASE config bit.
arch/x86/coco/tdx/tdx.c	Detects PAGE.RELEASE support, implements page release helper, and uses it before private→shared conversion.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Suppressed comments (2)

arch/x86/coco/tdx/tdx.c:351

• tdx_page_release_supported is initialized once during early boot and then treated as a read-only feature flag. Marking it __ro_after_init matches the hardening pattern used for similar CC globals (e.g., cc_vendor/cc_mask in arch/x86/coco/core.c) and prevents accidental/runtime modification.

static bool tdx_page_release_supported;

arch/x86/coco/tdx/tdx.c:410

• The _tdx_release_memory() definition exceeds the kernel's typical 80-column style and is inconsistent with nearby wrapped function signatures (e.g., tdx_enc_status_changed_phys()). Please wrap the parameters to keep the declaration readable and checkpatch-friendly.

static bool _tdx_release_memory(phys_addr_t start, phys_addr_t end, phys_addr_t *cur)
{

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

[Chris Oo (chris-oo)]

This looks reasonable to me. I assume we will drop these commits once we take a new kernel release and upstream has merged them? Have they merged in upstream?

[Dexuan Cui (dcui)]

This looks reasonable to me. I assume we will drop these commits once we take a new kernel release and upstream has merged them? Have they merged in upstream?

Intel hasn't upstreamed the change yet. I suppose Intel will upstream the change some day, but there is no ETA yet. Once Intel upstreams the change, we will drop the commit once we take a new kernel version that has this change from Intel.

[Dexuan Cui (dcui)]

BTW, the patch has been used by the host team for quite a while and they haven't seen any issues.