diff options
author | Kirill A. Shutemov <[email protected]> | 2024-06-14 12:59:00 +0300 |
---|---|---|
committer | Borislav Petkov (AMD) <[email protected]> | 2024-06-17 17:46:17 +0200 |
commit | db0936830a2fcc35e2b283275acf61b6d3ae1e11 (patch) | |
tree | 4601103ff96730ac98238d8875e3e6c16c80673f | |
parent | 6630cbce7cd7785f76b1055f33a71199ef28510b (diff) |
x86/acpi: Do not attempt to bring up secondary CPUs in the kexec case
ACPI MADT doesn't allow to offline a CPU after it was onlined. This limits
kexec: the second kernel won't be able to use more than one CPU.
To prevent a kexec kernel from onlining secondary CPUs, invalidate the mailbox
address in the ACPI MADT wakeup structure which prevents a kexec kernel to use
it.
This is safe as the booting kernel has the mailbox address cached already and
acpi_wakeup_cpu() uses the cached value to bring up the secondary CPUs.
Note: This is a Linux specific convention and not covered by the ACPI
specification.
Signed-off-by: Kirill A. Shutemov <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Reviewed-by: Kai Huang <[email protected]>
Reviewed-by: Kuppuswamy Sathyanarayanan <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Acked-by: Rafael J. Wysocki <[email protected]>
Tested-by: Tao Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
-rw-r--r-- | arch/x86/kernel/acpi/madt_wakeup.c | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/arch/x86/kernel/acpi/madt_wakeup.c b/arch/x86/kernel/acpi/madt_wakeup.c index 004801b9b151..30820f9de5af 100644 --- a/arch/x86/kernel/acpi/madt_wakeup.c +++ b/arch/x86/kernel/acpi/madt_wakeup.c @@ -14,6 +14,11 @@ static struct acpi_madt_multiproc_wakeup_mailbox *acpi_mp_wake_mailbox __ro_afte static int acpi_wakeup_cpu(u32 apicid, unsigned long start_ip) { + if (!acpi_mp_wake_mailbox_paddr) { + pr_warn_once("No MADT mailbox: cannot bringup secondary CPUs. Booting with kexec?\n"); + return -EOPNOTSUPP; + } + /* * Remap mailbox memory only for the first call to acpi_wakeup_cpu(). * @@ -64,6 +69,28 @@ static int acpi_wakeup_cpu(u32 apicid, unsigned long start_ip) return 0; } +static void acpi_mp_disable_offlining(struct acpi_madt_multiproc_wakeup *mp_wake) +{ + cpu_hotplug_disable_offlining(); + + /* + * ACPI MADT doesn't allow to offline a CPU after it was onlined. This + * limits kexec: the second kernel won't be able to use more than one CPU. + * + * To prevent a kexec kernel from onlining secondary CPUs invalidate the + * mailbox address in the ACPI MADT wakeup structure which prevents a + * kexec kernel to use it. + * + * This is safe as the booting kernel has the mailbox address cached + * already and acpi_wakeup_cpu() uses the cached value to bring up the + * secondary CPUs. + * + * Note: This is a Linux specific convention and not covered by the + * ACPI specification. + */ + mp_wake->mailbox_address = 0; +} + int __init acpi_parse_mp_wake(union acpi_subtable_headers *header, const unsigned long end) { @@ -77,7 +104,7 @@ int __init acpi_parse_mp_wake(union acpi_subtable_headers *header, acpi_mp_wake_mailbox_paddr = mp_wake->mailbox_address; - cpu_hotplug_disable_offlining(); + acpi_mp_disable_offlining(mp_wake); apic_update_callback(wakeup_secondary_cpu_64, acpi_wakeup_cpu); |