Re: [PATCH v7 12/13] ACPI / init: Invoke early ACPI initialization earlier
From: Dou Liyang
Date: Tue Jul 18 2017 - 05:44:54 EST
Hi Baoquan,
At 07/18/2017 04:45 PM, bhe@xxxxxxxxxx wrote:
On 07/18/17 at 02:08pm, Dou Liyang wrote:
Hi, Zheng
At 07/18/2017 01:18 PM, Zheng, Lv wrote:
Hi,
Can the problem be fixed by invoking acpi_put_table() for mapped DMAR table?
Invoking acpi_put_table() is my first choice. But it made the kernel
*panic* when we try to get the table again in intel_iommu_init() in
late stage.
I am also confused that:
There are two places where we used DMAR table in Linux:
1) In detect_intel_iommu() in ACPI early stage:
...
status = acpi_get_table(ACPI_SIG_DMAR, 0, &dmar_tbl);
....
if (dmar_tbl) {
acpi_put_table(dmar_tbl);
dmar_tbl = NULL;
}
2) In dmar_table_init() in ACPI late stage:
...
status = acpi_get_table(ACPI_SIG_DMAR, 0, &dmar_tbl);
...
As we know, dmar_table_init() is called by intel_iommu_init() and
intel_prepare_irq_remapping().
When I invoked acpi_put_table() in the intel_prepare_irq_remapping() in
early stage like 1) shows, kernel will panic.
That's because acpi_put_table() will make the table pointer be NULL,
while dmar_table_init() will skip parse_dmar_table() calling if
dmar_table_initialized is set to 1 in intel_prepare_irq_remapping().
Correctly.
I have considered and removed the *dmar_table_initialized* in this
situation. So, dmar_table_init() didn't skip parse_dmar_table()
calling.
I didn't dig into the cause, I think it is interesting, I will do it
right now and share with you later.
Dmar hardware support interrupt remapping and io remapping separately. But
intel_iommu_init() is called later than intel_prepare_irq_remapping().
So what if make dmar_table_init() a reentrant function? You can just
have a try, but maybe not a good idea, the dmar table will be parsed
twice.
Yes, It is precisely one reason that I gave up invoking
acpi_put_table().
Thanks,
dou.
Thanks,
dou.
Thanks
Lv
From: Dou Liyang [mailto:douly.fnst@xxxxxxxxxxxxxx]
Sent: Friday, July 14, 2017 1:53 PM
To: x86@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Cc: tglx@xxxxxxxxxxxxx; mingo@xxxxxxxxxx; hpa@xxxxxxxxx; ebiederm@xxxxxxxxxxxx; bhe@xxxxxxxxxx;
peterz@xxxxxxxxxxxxx; izumi.taku@xxxxxxxxxxxxxx; tokunaga.keiich@xxxxxxxxxxxxxx; Dou Liyang
<douly.fnst@xxxxxxxxxxxxxx>; linux-acpi@xxxxxxxxxxxxxxx; Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>; Zheng,
Lv <lv.zheng@xxxxxxxxx>; Julian Wollrath <jwollrath@xxxxxx>
Subject: [PATCH v7 12/13] ACPI / init: Invoke early ACPI initialization earlier
Linux uses acpi_early_init() to put the ACPI table management into
the late stage from the early stage where the mapped ACPI tables is
temporary and should be unmapped.
But, now initializing interrupt delivery mode should map and parse the
DMAR table earlier in the early stage. This causes an ACPI error when
Linux reallocates the ACPI root tables. Because Linux doesn't unmapped
the DMAR table after using in the early stage.
Invoke acpi_early_init() earlier before late_time_init(), Keep the DMAR
be mapped and parsed in late stage like before.
Reported-by: Xiaolong Ye <xiaolong.ye@xxxxxxxxx>
Signed-off-by: Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>
Cc: linux-acpi@xxxxxxxxxxxxxxx
Cc: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
Cc: Zheng, Lv <lv.zheng@xxxxxxxxx>
Cc: Julian Wollrath <jwollrath@xxxxxx>
---
Test in my own PC(Lenovo M4340).
Ask help for doing regression testing for the bug said in commit c4e1acbb35e4
("ACPI / init: Invoke early ACPI initialization later").
init/main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/init/main.c b/init/main.c
index df58a41..7a09467 100644
--- a/init/main.c
+++ b/init/main.c
@@ -654,12 +654,12 @@ asmlinkage __visible void __init start_kernel(void)
kmemleak_init();
setup_per_cpu_pageset();
numa_policy_init();
+ acpi_early_init();
if (late_time_init)
late_time_init();
calibrate_delay();
pidmap_init();
anon_vma_init();
- acpi_early_init();
#ifdef CONFIG_X86
if (efi_enabled(EFI_RUNTIME_SERVICES))
efi_enter_virtual_mode();
--
2.5.5