xen/arm: Do not route NS phys timer IRQ to Xen

At the moment, we route NS phys timer IRQ to Xen even though it does not
make use of this timer. Xen uses hypervisor timer for itself and the
physical timer is fully emulated, hence there is nothing that can trigger
such IRQ. This means that requesting/releasing IRQ ends up as a deadcode
as it has no impact on the functional behavior, whereas the code within
a handler ends up being unreachable. This is a left over from the early
days when the CNTHP IRQ was buggy on the HW model used for testing and we
had to use the CNTP instead.

Remove the calls to {request/release}_irq for this timer as well as the
code within the handler. Since timer_interrupt handler is now only used
by the CNTHP, refactor it as follows:
 - rename it to htimer_interrupt to reflect its purpose,
 - remove the IRQ affiliation test,
 - invert the condition to avoid indented code and use unlikely,
 - improve readability by adding new lines \btw code and comments.

Keep the calls to zero the CNTP_CTL_EL0 register for sanity and also
remove the corresponding perf counter definition.

Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>

diff --git a/xen/arch/arm/include/asm/perfc_defn.h b/xen/arch/arm/include/asm/perfc_defn.h
index 31f071222b24c91499710cb0c28577ce898dbbc1..3ab0391175d7fe70f7fa1d8415dc649d412a52f5 100644 (file)
--- a/xen/arch/arm/include/asm/perfc_defn.h
+++ b/xen/arch/arm/include/asm/perfc_defn.h
@@ -70,7 +70,6 @@ PERFCOUNTER(spis,                 "#SPIs")
 PERFCOUNTER(guest_irqs,           "#GUEST-IRQS")
 
 PERFCOUNTER(hyp_timer_irqs,   "Hypervisor timer interrupts")
-PERFCOUNTER(phys_timer_irqs,  "Physical timer interrupts")
 PERFCOUNTER(virt_timer_irqs,  "Virtual timer interrupts")
 PERFCOUNTER(maintenance_irqs, "Maintenance interrupts")
 

diff --git a/xen/arch/arm/time.c b/xen/arch/arm/time.c
index dec53b5f7d53a208dcd471a478b0088dd2879518..0054cf2b7b78b66af8b8e1cc90fb71871568d90d 100644 (file)
--- a/xen/arch/arm/time.c
+++ b/xen/arch/arm/time.c
@@ -220,27 +220,18 @@ int reprogram_timer(s_time_t timeout)
 }
 
 /* Handle the firing timer */
-static void timer_interrupt(int irq, void *dev_id, struct cpu_user_regs *regs)
+static void htimer_interrupt(int irq, void *dev_id, struct cpu_user_regs *regs)
 {
-    if ( irq == (timer_irq[TIMER_HYP_PPI]) &&
-         READ_SYSREG(CNTHP_CTL_EL2) & CNTx_CTL_PENDING )
-    {
-        perfc_incr(hyp_timer_irqs);
-        /* Signal the generic timer code to do its work */
-        raise_softirq(TIMER_SOFTIRQ);
-        /* Disable the timer to avoid more interrupts */
-        WRITE_SYSREG(0, CNTHP_CTL_EL2);
-    }
+    if ( unlikely(!(READ_SYSREG(CNTHP_CTL_EL2) & CNTx_CTL_PENDING)) )
+        return;
 
-    if ( irq == (timer_irq[TIMER_PHYS_NONSECURE_PPI]) &&
-         READ_SYSREG(CNTP_CTL_EL0) & CNTx_CTL_PENDING )
-    {
-        perfc_incr(phys_timer_irqs);
-        /* Signal the generic timer code to do its work */
-        raise_softirq(TIMER_SOFTIRQ);
-        /* Disable the timer to avoid more interrupts */
-        WRITE_SYSREG(0, CNTP_CTL_EL0);
-    }
+    perfc_incr(hyp_timer_irqs);
+
+    /* Signal the generic timer code to do its work */
+    raise_softirq(TIMER_SOFTIRQ);
+
+    /* Disable the timer to avoid more interrupts */
+    WRITE_SYSREG(0, CNTHP_CTL_EL2);
 }
 
 static void vtimer_interrupt(int irq, void *dev_id, struct cpu_user_regs *regs)
@@ -302,12 +293,10 @@ void init_timer_interrupt(void)
     WRITE_SYSREG(0, CNTHP_CTL_EL2);   /* Hypervisor's timer disabled */
     isb();
 
-    request_irq(timer_irq[TIMER_HYP_PPI], 0, timer_interrupt,
+    request_irq(timer_irq[TIMER_HYP_PPI], 0, htimer_interrupt,
                 "hyptimer", NULL);
     request_irq(timer_irq[TIMER_VIRT_PPI], 0, vtimer_interrupt,
                    "virtimer", NULL);
-    request_irq(timer_irq[TIMER_PHYS_NONSECURE_PPI], 0, timer_interrupt,
-                "phytimer", NULL);
 
     check_timer_irq_cfg(timer_irq[TIMER_HYP_PPI], "hypervisor");
     check_timer_irq_cfg(timer_irq[TIMER_VIRT_PPI], "virtual");
@@ -326,7 +315,6 @@ static void deinit_timer_interrupt(void)
 
     release_irq(timer_irq[TIMER_HYP_PPI], NULL);
     release_irq(timer_irq[TIMER_VIRT_PPI], NULL);
-    release_irq(timer_irq[TIMER_PHYS_NONSECURE_PPI], NULL);
 }
 
 /* Wait a set number of microseconds */