Revert "xen/x86: Workaround 64-bit hypervisor and 32-bit initial domain." and... (51faaf2b) · Commits · 戴 / test

arch/x86/xen/enlighten.c

+0 −60

Original line number	Diff line number	Diff line
		@@ -998,66 +998,7 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)

		return ret;
		}
		/*
		* If the MFN is not in the m2p (provided to us by the hypervisor) this
		* function won't do anything. In practice this means that the XenBus
		* MFN won't be available for the initial domain. */
		static unsigned long __init xen_reserve_mfn(unsigned long mfn)
		{
		unsigned long pfn, end_pfn = 0;

		if (!mfn)
		return end_pfn;

		pfn = mfn_to_pfn(mfn);
		if (phys_to_machine_mapping_valid(pfn)) {
		end_pfn = PFN_PHYS(pfn) + PAGE_SIZE;
		memblock_reserve(PFN_PHYS(pfn), end_pfn);
		}
		return end_pfn;
		}
		static void __init xen_reserve_internals(void)
		{
		unsigned long size;
		unsigned long last_phys = 0;

		if (!xen_pv_domain())
		return;

		/* xen_start_info does not exist in the M2P, hence can't use
		* xen_reserve_mfn. */
		memblock_reserve(__pa(xen_start_info), PAGE_SIZE);
		last_phys = __pa(xen_start_info) + PAGE_SIZE;

		last_phys = max(xen_reserve_mfn(PFN_DOWN(xen_start_info->shared_info)), last_phys);
		last_phys = max(xen_reserve_mfn(xen_start_info->store_mfn), last_phys);

		if (!xen_initial_domain())
		last_phys = max(xen_reserve_mfn(xen_start_info->console.domU.mfn), last_phys);

		if (xen_feature(XENFEAT_auto_translated_physmap))
		return;

		/*
		* ALIGN up to compensate for the p2m_page pointing to an array that
		* can partially filled (look in xen_build_dynamic_phys_to_machine).
		*/

		size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long));

		/* We could use xen_reserve_mfn here, but would end up looping quite
		* a lot (and call memblock_reserve for each PAGE), so lets just use
		* the easy way and reserve it wholesale. */
		memblock_reserve(__pa(xen_start_info->mfn_list), size);
		last_phys = max(__pa(xen_start_info->mfn_list) + size, last_phys);
		/* The pagetables are reserved in mmu.c */

		/* Under 64-bit hypervisor with a 32-bit domain, the hypervisor
		* offsets the pt_base by two pages. Hence the reservation that is done
		* in mmu.c misses two pages. We correct it here if we detect this. */
		if (last_phys < __pa(xen_start_info->pt_base))
		memblock_reserve(last_phys, __pa(xen_start_info->pt_base) - last_phys);
		}
		void xen_setup_shared_info(void)
		{
		if (!xen_feature(XENFEAT_auto_translated_physmap)) {
		@@ -1421,7 +1362,6 @@ asmlinkage void __init xen_start_kernel(void)
		xen_raw_console_write("mapping kernel into physical memory\n");
		pgd = xen_setup_kernel_pagetable(pgd, xen_start_info->nr_pages);

		xen_reserve_internals();
		/* Allocate and initialize top and mid mfn levels for p2m structure */
		xen_build_mfn_list_list();

arch/x86/xen/p2m.c

+0 −5

Original line number	Diff line number	Diff line
		@@ -388,11 +388,6 @@ void __init xen_build_dynamic_phys_to_machine(void)
		}

		m2p_override_init();

		/* NOTE: We cannot call memblock_reserve here for the mfn_list as there
		* isn't enough pieces to make it work (for one - we are still using the
		* Xen provided pagetable). Do it later in xen_reserve_internals.
		*/
		}

		unsigned long get_phys_to_machine(unsigned long pfn)

arch/x86/xen/setup.c

+27 −0

Original line number	Diff line number	Diff line
		@@ -424,6 +424,33 @@ char * __init xen_memory_setup(void)
		e820_add_region(ISA_START_ADDRESS, ISA_END_ADDRESS - ISA_START_ADDRESS,
		E820_RESERVED);

		/*
		* Reserve Xen bits:
		* - mfn_list
		* - xen_start_info
		* See comment above "struct start_info" in <xen/interface/xen.h>
		* We tried to make the the memblock_reserve more selective so
		* that it would be clear what region is reserved. Sadly we ran
		* in the problem wherein on a 64-bit hypervisor with a 32-bit
		* initial domain, the pt_base has the cr3 value which is not
		* neccessarily where the pagetable starts! As Jan put it: "
		* Actually, the adjustment turns out to be correct: The page
		* tables for a 32-on-64 dom0 get allocated in the order "first L1",
		* "first L2", "first L3", so the offset to the page table base is
		* indeed 2. When reading xen/include/public/xen.h's comment
		* very strictly, this is not a violation (since there nothing is said
		* that the first thing in the page table space is pointed to by
		* pt_base; I admit that this seems to be implied though, namely
		* do I think that it is implied that the page table space is the
		* range [pt_base, pt_base + nt_pt_frames), whereas that
		* range here indeed is [pt_base - 2, pt_base - 2 + nt_pt_frames),
		* which - without a priori knowledge - the kernel would have
		* difficulty to figure out)." - so lets just fall back to the
		* easy way and reserve the whole region.
		*/
		memblock_reserve(__pa(xen_start_info->mfn_list),
		xen_start_info->pt_base - xen_start_info->mfn_list);

		sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);

		return "Xen";

Admin message