arm64: Add CCA guest support

[sarah.walker2_arm.com]

Summary

Realm status is determined early in bootup. PSCI initialisation has been moved
to initarm() to faciliate this.

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

Sponsored by: Arm Ltd

[sarah.walker2_arm.com]

Remove PG_UNPROTECTED flag

[sarah.walker2_arm.com]

Update due to flag removal/reworking

[andrew]

I think we can split out the pmap and busdma parts into 2 new revisions (i.e. one for pmap, one for busdma)

sys/arm64/arm64/rsi.c

57

This should live in pmap.c, and be marked as __read_mostly, e.g. like pmap_sh_attr. It would be useful to have pa in the name to make it obvious it's to be applied to the physical address. If FEAT_LPA2 is enabled it may not work with a page table as bits 51:50 of the output address are in bits 9:8 of the page table.

175

To get all physical memory we will need a new function that doesn't exclude EXFLAG_NOALLOC memory (e.g. the kernel image). Something like the following:

size_t
physmem_all(vm_paddr_t *avail, size_t maxavail) 
{
        return (regions_to_avail(avail, 0, maxavail, 0, NULL, NULL));
}

physmem_avail builds the array of physical memory we can allocate from so will not be complete.

177

We could drop these printf calls, or put them behind bootverbose

[sarah.walker2_arm.com]

This review has been split into
https://reviews.freebsd.org/D56598 (RSI detection)
https://reviews.freebsd.org/D56599 (VM/PMAP changes)
https://reviews.freebsd.org/D56600 (SOCDEV_PA change)