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ANDROID: KVM: arm64: pkvm_module_ops documentation

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This structure is at the heart of the module support for pKVM. Add a
description to help anyone trying to create a module.

Bug: 312200309
Change-Id: Ie1d9043a6a94d15dd8ef25c6f0f8d442da26bc1f
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
This commit is contained in:
Vincent Donnefort 2023-11-07 17:32:15 +00:00
parent c331f5b7af
commit af85ead8ce
1 changed files with 101 additions and 0 deletions
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101
arch/arm64/include/asm/kvm_pkvm_module.h
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@ -16,6 +16,107 @@ enum pkvm_psci_notification {
};
#ifdef CONFIG_MODULES
/**
* struct pkvm_module_ops - pKVM modules callbacks
* @create_private_mapping: Map a memory region into the hypervisor private
* range. @haddr returns the virtual address where
* the mapping starts. It can't be unmapped. Host
* access permissions are unaffected.
* @alloc_module_va: Reserve a range of VA space in the hypervisor
* private range. This is handy for modules that
* need to map plugin code in a similar fashion to
* how pKVM maps module code. That space could also
* be used to map memory temporarily, when the
* fixmap granularity (PAGE_SIZE) is too small.
* @map_module_page: Used in conjunction with @alloc_module_va. When
* @is_protected is not set, the page is also
* unmapped from the host stage-2.
* @register_serial_driver: Register a driver for a serial interface. The
* framework only needs a single callback
* @hyp_putc_cb which is expected to print a single
* character.
* @puts: If a serial interface is registered, print a
* string, else does nothing.
* @putx64: If a serial interface is registered, print a
* 64-bit number, else does nothing.
* @fixmap_map: Map a page in the per-CPU hypervisor fixmap.
* This is intended to be used for temporary
* mappings in the hypervisor VA space.
* @fixmap_unmap must be called between each
* mapping to do cache maintenance and ensure the
* new mapping is visible.
* @fixmap_unmap: Unmap a page from the hypervisor fixmap. This
* call is required between each @fixmap_map().
* @linear_map_early: Map a large portion of memory into the
* hypervisor linear VA space. This is intended to
* be used only for module bootstrap and must be
* unmapped before the host is deprivilged.
* @linear_unmap_early: See @linear_map_early.
* @flush_dcache_to_poc: Clean the data cache to the point of coherency.
* This is not a requirement for any other of the
* pkvm_module_ops callbacks.
* @update_hcr_el2: Modify the running value of HCR_EL2. pKVM will
* save/restore the new value across power
* management transitions.
* @update_hfgwtr_el2: Modify the running value of HFGWTR_EL2. pKVM
* will save/restore the new value across power
* management transitions.
* @register_host_perm_fault_handler:
* @cb is called whenever the host generates an
* abort with the fault status code Permission
* Fault. Returning -EPERM lets pKVM handle the
* abort. This is useful when a module changes the
* host stage-2 permissions for certain pages.
* @host_stage2_mod_prot: Apply @prot to the page @pfn. This requires a
* permission fault handler to be registered (see
* @register_host_perm_fault_handler), otherwise
* pKVM will be unable to handle this fault and the
* CPU will be stuck in an infinite loop.
* @host_stage2_get_leaf: Query the host's stage2 page-table entry for
* the page @phys.
* @register_host_smc_handler: @cb is called whenever the host issues an SMC
* pKVM couldn't handle. If @cb returns false, the
* SMC will be forwarded to EL3.
* @register_default_trap_handler:
* @cb is called whenever EL2 traps EL1 and pKVM
* has not handled it. If @cb returns false, the
* hypervisor will panic. This trap handler must be
* registered whenever changes are made to HCR
* (@update_hcr_el2) or HFGWTR
* (@update_hfgwtr_el2).
* @register_illegal_abt_notifier:
* To notify the module of a pending illegal abort
* from the host. On @cb return, the abort will be
* injected back into the host.
* @register_psci_notifier: To notify the module of a pending PSCI event.
* @register_hyp_panic_notifier:
* To notify the module of a pending hypervisor
* panic. On return from @cb, the panic will occur.
* @host_donate_hyp: The page @pfn is unmapped from the host and
* full control is given to the hypervisor.
* @hyp_donate_host: The page @pfn whom control has previously been
* given to the hypervisor (@host_donate_hyp) is
* given back to the host.
* @host_share_hyp: The page @pfn will be shared between the host
* and the hypervisor. Must be followed by
* @pin_shared_mem.
* @host_unshare_hyp: The page @pfn will be unshared and unmapped from
* the hypervisor. Must be called after
* @unpin_shared_mem.
* @pin_shared_mem: After @host_share_hyp, the newly shared page is
* still owned by the host. @pin_shared_mem will
* prevent the host from reclaiming that page until
* the hypervisor releases it (@unpin_shared_mem)
* @unpin_shared_mem: Enable the host to reclaim the shared memory
* (@host_unshare_hyp).
* @memcpy: Same as kernel memcpy, but use hypervisor VAs.
* @memset: Same as kernel memset, but use a hypervisor VA.
* @hyp_pa: Return the physical address for a hypervisor
* virtual address in the linear range.
* @hyp_va: Convert a physical address into a virtual one.
* @kern_hyp_va: Convert a kernel virtual address into an
* hypervisor virtual one.
*/
struct pkvm_module_ops {
int (*create_private_mapping)(phys_addr_t phys, size_t size,
enum kvm_pgtable_prot prot,