KVM/TDX: Get/put PAMT pages when (un)mapping private memory

Add Dynamic PAMT support to KVM's S-EPT MMU by "getting" a PAMT page when
adding guest memory (PAGE.ADD or PAGE.AUG), and "putting" the page when
removing guest memory (PAGE.REMOVE).

To access the per-vCPU PAMT caches without plumbing @vcpu throughout the
TDP MMU, begrudgingly use kvm_get_running_vcpu() to get the vCPU, and bug
the VM if KVM attempts to set an S-EPT leaf without an active vCPU.  KVM
only supports creating _new_ mappings in page (pre)fault paths, all of
which require an active vCPU.

The PAMT memory holds metadata for TDX protected memory. With Dynamic
PAMT, PAMT_4K is allocated on demand. The kernel supplies the TDX module
with a few pages that cover 2MB of host physical memory.

Releases are balanced via tdx_pamt_put(): every control-page free goes
through tdx_free_control_page(), and guest data pages are put directly on
the successful tdh_mem_page_remove() path and in the
tdx_mem_page_add/aug() error path.

Co-developed-by: Sean Christopherson <seanjc@google.com>
[rick: enhance log, reviewing, rebase, with help from AI tooling]
Co-developed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Tony Lindgren <tony.lindgren@linux.intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Vishal Annapurve <vannapurve@google.com>
Acked-by: Sohil Mehta <sohil.mehta@intel.com>
Acked-by: Sean Christopherson <seanjc@google.com>
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Link: https://patch.msgid.link/20260904215841.303070-9-rick.p.edgecombe@intel.com

0 files changed, 0 insertions, 0 deletions