Commit 806c312e authored by Konrad Rzeszutek Wilk's avatar Konrad Rzeszutek Wilk
Browse files

xen/x86: Workaround 64-bit hypervisor and 32-bit initial domain. 



If a 64-bit hypervisor is booted with a 32-bit initial domain,
the hypervisor deals with the initial domain as "compat" and
does some extra adjustments (like pagetables are 4 bytes instead
of 8). It also adjusts the xen_start_info->pt_base incorrectly.

When booted with a 32-bit hypervisor (32-bit initial domain):
..
(XEN)  Start info:    cf831000->cf83147c
(XEN)  Page tables:   cf832000->cf8b5000
..
[    0.000000] PT: cf832000 (f832000)
[    0.000000] Reserving PT: f832000->f8b5000

And with a 64-bit hypervisor:
(XEN)  Start info:    00000000cf831000->00000000cf8314b4
(XEN)  Page tables:   00000000cf832000->00000000cf8b6000

[    0.000000] PT: cf834000 (f834000)
[    0.000000] Reserving PT: f834000->f8b8000

To deal with this, we keep keep track of the highest physical
address we have reserved via memblock_reserve. If that address
does not overlap with pt_base, we have a gap which we reserve.

Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 59b29440

arch/x86/xen/enlighten.c

+21 −9
Original line number Diff line number Diff line
@@ -1002,19 +1002,24 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high) 
 * 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 void __init xen_reserve_mfn(unsigned long mfn)

static unsigned long __init xen_reserve_mfn(unsigned long mfn)

{

	unsigned long pfn;

	unsigned long pfn, end_pfn = 0;



	if (!mfn)

		return;

		return end_pfn;



	pfn = mfn_to_pfn(mfn);

	if (phys_to_machine_mapping_valid(pfn))

		memblock_reserve(PFN_PHYS(pfn), PAGE_SIZE);

	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;
@@ -1022,12 +1027,13 @@ static void __init xen_reserve_internals(void) 
	/* 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;



	xen_reserve_mfn(PFN_DOWN(xen_start_info->shared_info));

	xen_reserve_mfn(xen_start_info->store_mfn);

	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())

		xen_reserve_mfn(xen_start_info->console.domU.mfn);

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



	if (xen_feature(XENFEAT_auto_translated_physmap))

		return;
@@ -1043,8 +1049,14 @@ static void __init xen_reserve_internals(void) 
	 * 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)

{

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