apic: disable reentrancy detection for apic-msi

[PATCH] apic: disable reentrancy detection for apic-msi

Alexander Bulekov posted 1 patch 1 year ago

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Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20230427135233.2973922-1-alxndr@bu.edu

Maintainers: "Michael S. Tsirkin" <mst@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>

hw/intc/apic.c | 7 +++++++
1 file changed, 7 insertions(+)

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[PATCH] apic: disable reentrancy detection for apic-msi

Posted by Alexander Bulekov 1 year ago

As the code is designed for re-entrant calls to apic-msi, mark apic-msi
as reentrancy-safe.

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
---
Based-on: <20230426161951.2948996-1-alxndr@bu.edu>

 hw/intc/apic.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/intc/apic.c b/hw/intc/apic.c
index 20b5a94073..ac3d47d231 100644
--- a/hw/intc/apic.c
+++ b/hw/intc/apic.c
@@ -885,6 +885,13 @@ static void apic_realize(DeviceState *dev, Error **errp)
     memory_region_init_io(&s->io_memory, OBJECT(s), &apic_io_ops, s, "apic-msi",
                           APIC_SPACE_SIZE);
 
+    /*
+     * apic-msi's apic_mem_write can call into ioapic_eoi_broadcast, which can
+     * write back to apic-msi. As such mark the apic-msi region re-entrancy
+     * safe.
+     */
+    s->io_memory.disable_reentrancy_guard = true;
+
     s->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, apic_timer, s);
     local_apics[s->id] = s;
 
-- 
2.39.0

Re: [PATCH] apic: disable reentrancy detection for apic-msi

Posted by Darren Kenny 1 year ago

On Thursday, 2023-04-27 at 09:52:33 -04, Alexander Bulekov wrote:
> As the code is designed for re-entrant calls to apic-msi, mark apic-msi
> as reentrancy-safe.
>
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>

Reviewed-by: Darren Kenny <darren.kenny@oracle.com>

> ---
> Based-on: <20230426161951.2948996-1-alxndr@bu.edu>
>
>  hw/intc/apic.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/hw/intc/apic.c b/hw/intc/apic.c
> index 20b5a94073..ac3d47d231 100644
> --- a/hw/intc/apic.c
> +++ b/hw/intc/apic.c
> @@ -885,6 +885,13 @@ static void apic_realize(DeviceState *dev, Error **errp)
>      memory_region_init_io(&s->io_memory, OBJECT(s), &apic_io_ops, s, "apic-msi",
>                            APIC_SPACE_SIZE);
>  
> +    /*
> +     * apic-msi's apic_mem_write can call into ioapic_eoi_broadcast, which can
> +     * write back to apic-msi. As such mark the apic-msi region re-entrancy
> +     * safe.
> +     */
> +    s->io_memory.disable_reentrancy_guard = true;
> +
>      s->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, apic_timer, s);
>      local_apics[s->id] = s;
>  
> -- 
> 2.39.0