xen/mmu: Remove from __ka space PMD entries for pagetables. (3aca7fbc) · Commits · 戴 / test

Please first read the description in "xen/mmu: Copy and revector the P2M tree." At this stage, the __ka address space (which is what the old P2M tree was using) is partially disassembled. The cleanup_highmap has removed the PMD entries from 0-16MB and anything past _brk_end up to the max_pfn_mapped (which is the end of the ramdisk). The xen_remove_p2m_tree and code around has ripped out the __ka for the old P2M array. Here we continue on doing it to where the Xen page-tables were. It is safe to do it, as the page-tables are addressed using __va. For good measure we delete anything that is within MODULES_VADDR and up to the end of the PMD. At this point the __ka only contains PMD entries for the start of the kernel up to __brk. [v1: Per Stefano's suggestion wrapped the MODULES_VADDR in debug] Signed-off-by:

Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/xen/mmu.c

+19 −0

Original line number	Diff line number	Diff line
		@@ -1240,6 +1240,25 @@ static void __init xen_pagetable_setup_done(pgd_t *base)
		xen_start_info->mfn_list = new_mfn_list;
		}
		}
		/* At this stage, cleanup_highmap has already cleaned __ka space
		* from _brk_limit way up to the max_pfn_mapped (which is the end of
		* the ramdisk). We continue on, erasing PMD entries that point to page
		* tables - do note that they are accessible at this stage via __va.
		* For good measure we also round up to the PMD - which means that if
		* anybody is using __ka address to the initial boot-stack - and try
		* to use it - they are going to crash. The xen_start_info has been
		* taken care of already in xen_setup_kernel_pagetable. */
		addr = xen_start_info->pt_base;
		size = roundup(xen_start_info->nr_pt_frames * PAGE_SIZE, PMD_SIZE);

		xen_cleanhighmap(addr, addr + size);
		xen_start_info->pt_base = (unsigned long)__va(__pa(xen_start_info->pt_base));
		#ifdef DEBUG
		/* This is superflous and is not neccessary, but you know what
		* lets do it. The MODULES_VADDR -> MODULES_END should be clear of
		* anything at this stage. */
		xen_cleanhighmap(MODULES_VADDR, roundup(MODULES_VADDR, PUD_SIZE) - 1);
		#endif
		#endif
		xen_post_allocator_init();
		}

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