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

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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: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Konrad Rzeszutek Wilk 2012-08-21 14:31:24 -04:00
parent 59b294403e
commit 806c312e50
1 changed files with 21 additions and 9 deletions
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30
arch/x86/xen/enlighten.c
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@ -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)
{