Re: [kvm-unit-tests PATCH v2] x86: Reset lapic after boot

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On 06/27/2019 03:39 AM, Nadav Amit wrote:
Do not assume that the local APIC is in a xAPIC mode after reset.
Instead reset it first, since it might be in x2APIC mode, from which a
transition in xAPIC is invalid.

s/transition in/transition to/


To use reset_apic(), change it to use xapic_write(), in order to make safe to use
while apic_ops might change concurrently by x2apic_enable().

s/x2apic_enable/enable_x2apic/


Cc: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
Signed-off-by: Nadav Amit <nadav.amit@xxxxxxxxx>
---
  lib/x86/apic.c | 2 +-
  x86/cstart64.S | 2 ++
  2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/x86/apic.c b/lib/x86/apic.c
index 1514730..b3e39ae 100644
--- a/lib/x86/apic.c
+++ b/lib/x86/apic.c
@@ -164,7 +164,7 @@ void reset_apic(void)
  {
      disable_apic();
      wrmsr(MSR_IA32_APICBASE, rdmsr(MSR_IA32_APICBASE) | APIC_EN);
-    apic_write(APIC_SPIV, 0x1ff);
+    xapic_write(APIC_SPIV, 0x1ff);
  }
u32 ioapic_read_reg(unsigned reg)
diff --git a/x86/cstart64.S b/x86/cstart64.S
index 9791282..1889c6b 100644
--- a/x86/cstart64.S
+++ b/x86/cstart64.S
@@ -228,6 +228,7 @@ save_id:
  	retq
ap_start64:
+	call reset_apic
  	call load_tss
  	call enable_apic
  	call save_id
@@ -240,6 +241,7 @@ ap_start64:
  	jmp 1b
start64:
+	call reset_apic
  	call load_tss
  	call mask_pic_interrupts
  	call enable_apic

Except the above minor things,

Reviewed-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>



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