The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: ab84ba647f2c94ac4d0c3fc6951c49f08aa1fcf7
Gitweb: https://git.kernel.org/tip/ab84ba647f2c94ac4d0c3fc6951c49f08aa1fcf7
Author: Zhiquan Li <zhiquan1.li@xxxxxxxxx>
AuthorDate: Mon, 05 Aug 2024 18:35:31 +08:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Wed, 07 Aug 2024 20:04:38 +02:00
x86/acpi: Remove __ro_after_init from acpi_mp_wake_mailbox
On a platform using the "Multiprocessor Wakeup Structure"[1] to startup
secondary CPUs the control processor needs to memremap() the physical
address of the MP Wakeup Structure mailbox to the variable
acpi_mp_wake_mailbox, which holds the virtual address of mailbox.
To wake up the AP the control processor writes the APIC ID of AP, the
wakeup vector and the ACPI_MP_WAKE_COMMAND_WAKEUP command into the mailbox.
Current implementation doesn't consider the case which restricts boot time
CPU bringup to 1 with the kernel parameter "maxcpus=1" and brings other
CPUs online later from user space as it sets acpi_mp_wake_mailbox to
read-only after init. So when the first AP is tried to brought online
after init, the attempt to update the variable results in a kernel panic.
The memremap() call that initializes the variable cannot be moved into
acpi_parse_mp_wake() because memremap() is not functional at that point in
the boot process. Also as the APs might never be brought up, keep the
memremap() call in acpi_wakeup_cpu() so that the operation only takes place
when needed.
Fixes: 24dd05da8c79 ("x86/apic: Mark acpi_mp_wake_* variables as __ro_after_init")
Signed-off-by: Zhiquan Li <zhiquan1.li@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/all/20240805103531.1230635-1-zhiquan1.li@xxxxxxxxx
---
arch/x86/kernel/acpi/madt_wakeup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/acpi/madt_wakeup.c b/arch/x86/kernel/acpi/madt_wakeup.c
index 6cfe762..d5ef621 100644
--- a/arch/x86/kernel/acpi/madt_wakeup.c
+++ b/arch/x86/kernel/acpi/madt_wakeup.c
@@ -19,7 +19,7 @@
static u64 acpi_mp_wake_mailbox_paddr __ro_after_init;
/* Virtual address of the Multiprocessor Wakeup Structure mailbox */
-static struct acpi_madt_multiproc_wakeup_mailbox *acpi_mp_wake_mailbox __ro_after_init;
+static struct acpi_madt_multiproc_wakeup_mailbox *acpi_mp_wake_mailbox;
static u64 acpi_mp_pgd __ro_after_init;
static u64 acpi_mp_reset_vector_paddr __ro_after_init;
|