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SubjectRe: [Xen-devel] [PATCH] xen/boot: Disable BIOS SMP MP table search.
>>> On 19.09.12 at 15:27, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote:
> As the initial domain we are able to search/map certain regions
> of memory to harvest configuration data. For all low-level we
> use ACPI tables - for interrupts we use exclusively ACPI _PRT
> (so DSDT) and MADT for INT_SRC_OVR.
>
> The SMP MP table is not used at all. As a matter of fact we do
> not even support machines that only have SMP MP but no ACPI tables.
>
> Lets follow how Moorestown does it and just disable searching
> for BIOS SMP tables.
>
> This also fixes an issue on HP Proliant BL680c G5 and DL380 G6:
>
> 9f->100 for 1:1 PTE
> Freeing 9f-100 pfn range: 97 pages freed
> 1-1 mapping on 9f->100
> .. snip..
> e820: BIOS-provided physical RAM map:
> Xen: [mem 0x0000000000000000-0x000000000009efff] usable
> Xen: [mem 0x000000000009f400-0x00000000000fffff] reserved
> Xen: [mem 0x0000000000100000-0x00000000cfd1dfff] usable
> .. snip..
> Scan for SMP in [mem 0x00000000-0x000003ff]
> Scan for SMP in [mem 0x0009fc00-0x0009ffff]
> Scan for SMP in [mem 0x000f0000-0x000fffff]
> found SMP MP-table at [mem 0x000f4fa0-0x000f4faf] mapped at [ffff8800000f4fa0]
> (XEN) mm.c:908:d0 Error getting mfn 100 (pfn 5555555555555555) from L1 entry
> 0000000000100461 for l1e_owner=0, pg_owner=0
> (XEN) mm.c:4995:d0 ptwr_emulate: could not get_page_from_l1e()
> BUG: unable to handle kernel NULL pointer dereference at (null)
> IP: [<ffffffff81ac07e2>] xen_set_pte_init+0x66/0x71
> . snip..
> Pid: 0, comm: swapper Not tainted 3.6.0-rc6upstream-00188-gb6fb969-dirty #2 HP
> ProLiant BL680c G5
> .. snip..
> Call Trace:
> [<ffffffff81ad31c6>] __early_ioremap+0x18a/0x248
> [<ffffffff81624731>] ? printk+0x48/0x4a
> [<ffffffff81ad32ac>] early_ioremap+0x13/0x15
> [<ffffffff81acc140>] get_mpc_size+0x2f/0x67
> [<ffffffff81acc284>] smp_scan_config+0x10c/0x136
> [<ffffffff81acc2e4>] default_find_smp_config+0x36/0x5a
> [<ffffffff81ac3085>] setup_arch+0x5b3/0xb5b
> [<ffffffff81624731>] ? printk+0x48/0x4a
> [<ffffffff81abca7f>] start_kernel+0x90/0x390
> [<ffffffff81abc356>] x86_64_start_reservations+0x131/0x136
> [<ffffffff81abfa83>] xen_start_kernel+0x65f/0x661
> (XEN) Domain 0 crashed: 'noreboot' set - not rebooting.
>
> which is that ioremap would end up mapping 0xff using _PAGE_IOMAP
> (which is what early_ioremap sticks as a flag) - which meant
> we would get MFN 0xFF (pte ff461, which is OK), and then it would
> also map 0x100 (b/c ioremap tries to get page aligned request, and
> it was trying to map 0xf4fa0 + PAGE_SIZE - so it mapped the next page)
> as _PAGE_IOMAP. Since 0x100 is actually a RAM page, and the _PAGE_IOMAP
> bypasses the P2M lookup we would happily set the PTE to 1000461.
> Xen would deny the request since we do not have access to the
> Machine Frame Number (MFN) of 0x100. The P2M[0x100] is for example
> 0x80140.
>
> CC: stable@kernel.org
> Fixes-Oracle-Bugzilla:
> https://bugzilla.oracle.com/bugzilla/show_bug.cgi?id=13665
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Acked-by: Jan Beulich <jbeulich@suse.com>

> ---
> arch/x86/xen/enlighten.c | 4 ++++
> 1 files changed, 4 insertions(+), 0 deletions(-)
>
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index 9642d4a..1fbe75a 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1452,6 +1452,10 @@ asmlinkage void __init xen_start_kernel(void)
> pci_request_acs();
>
> xen_acpi_sleep_register();
> +
> + /* Avoid searching for BIOS MP tables */
> + x86_init.mpparse.find_smp_config = x86_init_noop;
> + x86_init.mpparse.get_smp_config = x86_init_uint_noop;
> }
> #ifdef CONFIG_PCI
> /* PCI BIOS service won't work from a PV guest. */
> --
> 1.7.7.6
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel





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