[xen stable-4.21] x86/HPET: channel handling in hpet_broadcast_resume()

[patchbot@xxxxxxx]

commit 2d1a11a50dcfede32e3ad4a577371df73312385d
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Mon Apr 20 12:28:35 2026 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Apr 20 12:28:35 2026 +0200

    x86/HPET: channel handling in hpet_broadcast_resume()
    
    The per-channel ENABLE bit is to solely be driven by hpet_enable_channel()
    and hpet_msi_{,un}mask(). It doesn't need setting immediately. Except for
    the (possible) channel put in legacy mode we don't do so during boot
    either.
    
    Instead reset ->arch.cpu_mask, to avoid msi_compose_msg() yielding an
    all-zero message (when the passed in CPU mask has no online CPUs). Nothing
    would later call msi_compose_msg() / hpet_msi_write(), and hence nothing
    would later produce a well-formed message template in
    hpet_events[].msi.msg.
    
    Fixes: 15aa6c67486c ("amd iommu: use base platform MSI implementation")
    Reported-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Tested-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
    Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    master commit: c4d51191954c53590767c26e501e6dadf923bc47
    master date: 2026-04-16 10:44:16 +0200
---
 xen/arch/x86/hpet.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hpet.c b/xen/arch/x86/hpet.c
index a69abe2650..918fab774d 100644
--- a/xen/arch/x86/hpet.c
+++ b/xen/arch/x86/hpet.c
@@ -705,12 +705,18 @@ void hpet_broadcast_resume(void)
     for ( i = 0; i < n; i++ )
     {
         if ( hpet_events[i].msi.irq >= 0 )
-            __hpet_setup_msi_irq(irq_to_desc(hpet_events[i].msi.irq));
+        {
+            struct irq_desc *desc = irq_to_desc(hpet_events[i].msi.irq);
+
+            cpumask_copy(desc->arch.cpu_mask, cpumask_of(smp_processor_id()));
+
+            __hpet_setup_msi_irq(desc);
+        }
 
         /* set HPET Tn as oneshot */
         cfg = hpet_read32(HPET_Tn_CFG(hpet_events[i].idx));
         cfg &= ~(HPET_TN_LEVEL | HPET_TN_PERIODIC);
-        cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
+        cfg |= HPET_TN_32BIT;
         if ( !(hpet_events[i].flags & HPET_EVT_LEGACY) )
             cfg |= HPET_TN_FSB;
         hpet_write32(cfg, HPET_Tn_CFG(hpet_events[i].idx));
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.21