[PATCH] x86/vhpet: fix RTC special casing

[PATCH] x86/vhpet: fix RTC special casing

[Roger Pau Monne]

Restore setting the virtual timer callback private data to NULL if the
timer is not level triggered. This fixes the special casing done in
pt_update_irq so that the RTC interrupt when originating from the HPET
is suspended if the interrupt source is masked.

Note the RTC special casing done in pt_update_irq should only apply to
the RTC interrupt originating from the emulated RTC device (which does
set the callback private data), as in that case the callback itself
will destroy the virtual timer if the interrupt is ignored.

While there also use RTC_IRQ instead of 8 when the HPET is configured
in LegacyReplacement Mode.

Fixes: be07023be115 ("x86/vhpet: add support for level triggered interrupts")
Reported-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
 xen/arch/x86/hvm/hpet.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/hpet.c b/xen/arch/x86/hvm/hpet.c
index ca94e8b4538..ee756abb824 100644
--- a/xen/arch/x86/hvm/hpet.c
+++ b/xen/arch/x86/hvm/hpet.c
@@ -22,6 +22,7 @@
 #include <asm/hvm/trace.h>
 #include <asm/current.h>
 #include <asm/hpet.h>
+#include <asm/mc146818rtc.h>
 #include <xen/sched.h>
 #include <xen/event.h>
 #include <xen/trace.h>
@@ -290,7 +291,7 @@ static void hpet_set_timer(HPETState *h, unsigned int tn,
         /* if LegacyReplacementRoute bit is set, HPET specification requires
            timer0 be routed to IRQ0 in NON-APIC or IRQ2 in the I/O APIC,
            timer1 be routed to IRQ8 in NON-APIC or IRQ8 in the I/O APIC. */
-        irq = (tn == 0) ? 0 : 8;
+        irq = (tn == 0) ? 0 : RTC_IRQ;
         h->pt[tn].source = PTSRC_isa;
     }
     else
@@ -318,7 +319,8 @@ static void hpet_set_timer(HPETState *h, unsigned int tn,
                          hpet_tick_to_ns(h, diff),
                          oneshot ? 0 : hpet_tick_to_ns(h, h->hpet.period[tn]),
                          irq, timer_level(h, tn) ? hpet_timer_fired : NULL,
-                         (void *)(unsigned long)tn, timer_level(h, tn));
+                         timer_level(h, tn) ? (void *)(unsigned long)tn : NULL,
+                         timer_level(h, tn));
 }
 
 static inline uint64_t hpet_fixup_reg(
-- 
2.31.1

Re: [PATCH] x86/vhpet: fix RTC special casing

[Jan Beulich]

On 04.05.2021 10:42, Roger Pau Monne wrote:
> Restore setting the virtual timer callback private data to NULL if the
> timer is not level triggered. This fixes the special casing done in
> pt_update_irq so that the RTC interrupt when originating from the HPET
> is suspended if the interrupt source is masked.
> 
> Note the RTC special casing done in pt_update_irq should only apply to
> the RTC interrupt originating from the emulated RTC device (which does
> set the callback private data), as in that case the callback itself
> will destroy the virtual timer if the interrupt is ignored.
> 
> While there also use RTC_IRQ instead of 8 when the HPET is configured
> in LegacyReplacement Mode.
> 
> Fixes: be07023be115 ("x86/vhpet: add support for level triggered interrupts")
> Reported-by: Jan Beulich <jbeulich@suse.com>
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>

Reviewed-by: Jan Beulich <jbeulich@suse.com>

> @@ -318,7 +319,8 @@ static void hpet_set_timer(HPETState *h, unsigned int tn,
>                           hpet_tick_to_ns(h, diff),
>                           oneshot ? 0 : hpet_tick_to_ns(h, h->hpet.period[tn]),
>                           irq, timer_level(h, tn) ? hpet_timer_fired : NULL,
> -                         (void *)(unsigned long)tn, timer_level(h, tn));
> +                         timer_level(h, tn) ? (void *)(unsigned long)tn : NULL,
> +                         timer_level(h, tn));

Depending on what further changes to this call may be planned, it
may help readability if we split the call into a level and an edge
one.

Jan