Commit-ID: 2640da4cccf5cc613bf26f0998b9e340f4b5f69c
Gitweb: https://git.kernel.org/tip/2640da4cccf5cc613bf26f0998b9e340f4b5f69c
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Mon, 22 Jul 2019 20:47:08 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Thu, 25 Jul 2019 16:11:56 +0200
x86/apic: Soft disable APIC before initializing it
If the APIC was already enabled on entry of setup_local_APIC() then
disabling it soft via the SPIV register makes a lot of sense.
That masks all LVT entries and brings it into a well defined state.
Otherwise previously enabled LVTs which are not touched in the setup
function stay unmasked and might surprise the just booting kernel.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20190722105219.068290579@xxxxxxxxxxxxx
---
arch/x86/kernel/apic/apic.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index fa0846d4e000..621992de49ee 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1522,6 +1522,14 @@ static void setup_local_APIC(void)
return;
}
+ /*
+ * If this comes from kexec/kcrash the APIC might be enabled in
+ * SPIV. Soft disable it before doing further initialization.
+ */
+ value = apic_read(APIC_SPIV);
+ value &= ~APIC_SPIV_APIC_ENABLED;
+ apic_write(APIC_SPIV, value);
+
#ifdef CONFIG_X86_32
/* Pound the ESR really hard over the head with a big hammer - mbligh */
if (lapic_is_integrated() && apic->disable_esr) {
|