On 05/07/2013 07:50 AM, Scott Wood wrote:
On 05/05/2013 10:13:17 PM, tiejun.chen wrote:
On 05/06/2013 11:10 AM, Tiejun Chen wrote:
For the external interrupt, the decrementer exception and the doorbell
excpetion, we also need to soft-disable interrupts while doing as host
interrupt handlers since the DO_KVM hook is always performed to skip
EXCEPTION_COMMON then miss this original chance with the 'ints' (INTS_DISABLE).
http://patchwork.ozlabs.org/patch/241344/
http://patchwork.ozlabs.org/patch/241412/
:-)
I'm observing the same behaviour as well:
WARN_ON_ONCE(!irqs_disabled());
Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxxxxxx>
---
arch/powerpc/kvm/bookehv_interrupts.S | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/powerpc/kvm/bookehv_interrupts.S
b/arch/powerpc/kvm/bookehv_interrupts.S
index e8ed7d6..2fd62bf 100644
--- a/arch/powerpc/kvm/bookehv_interrupts.S
+++ b/arch/powerpc/kvm/bookehv_interrupts.S
@@ -33,6 +33,8 @@
#ifdef CONFIG_64BIT
#include <asm/exception-64e.h>
+#include <asm/hw_irq.h>
+#include <asm/irqflags.h>
#else
#include "../kernel/head_booke.h" /* for THREAD_NORMSAVE() */
#endif
@@ -469,6 +471,13 @@ _GLOBAL(kvmppc_resume_host)
PPC_LL r3, HOST_RUN(r1)
mr r5, r14 /* intno */
mr r14, r4 /* Save vcpu pointer. */
+#ifdef CONFIG_64BIT
+ /* Should we soft-disable interrupts? */
+ andi. r6, r5, BOOKE_INTERRUPT_EXTERNAL | BOOKE_INTERRUPT_DECREMENTER
| BOOKE_INTERRUPT_DOORBELL
+ beq skip_soft_dis
+ SOFT_DISABLE_INTS(r7,r8)
+skip_soft_dis:
+#endif
Why wouldn't we always disable them? kvmppc_handle_exit() will enable
interrupts when it's ready.
This only disable soft interrupt for kvmppc_restart_interrupt() that restarts
interrupts if they were meant for the host:
a. SOFT_DISABLE_INTS() only for BOOKE_INTERRUPT_EXTERNAL |
BOOKE_INTERRUPT_DECREMENTER | BOOKE_INTERRUPT_DOORBELL
b. bl kvmppc_handle_exit
c. kvmppc_handle_exit()
{
int r = RESUME_HOST;
int s;
/* update before a new last_exit_type is rewritten */
kvmppc_update_timing_stats(vcpu);
/* restart interrupts if they were meant for the host */
kvmppc_restart_interrupt(vcpu, exit_nr);
local_irq_enable(); ==> Enable again.
....
And shouldn't we handle kvmppc_restart_interrupt() like the original HOST flow?
#define MASKABLE_EXCEPTION(trapnum, intnum, label, hdlr, ack) \
START_EXCEPTION(label); \
NORMAL_EXCEPTION_PROLOG(trapnum, intnum, PROLOG_ADDITION_MASKABLE)\
EXCEPTION_COMMON(trapnum, PACA_EXGEN, *INTS_DISABLE*) \
...
So I think this should be reasonable :)
Tiejun
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