[xen master] x86/ioapic: Fix signed shifts in io_apic.c

[patchbot@xxxxxxx]

commit c5746b021e573184fb92b601a0e93a295485054e
Author:     Matthew Barnes <matthew.barnes@xxxxxxxxx>
AuthorDate: Thu Jun 20 16:36:46 2024 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Fri Jun 21 15:09:26 2024 +0100

    x86/ioapic: Fix signed shifts in io_apic.c
    
    There exists bitshifts in the IOAPIC code where signed integers are
    shifted to the left by up to 31 bits, which is undefined behaviour.
    
    This patch fixes this by changing the integers from signed to unsigned.
    
    Signed-off-by: Matthew Barnes <matthew.barnes@xxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Release-Acked-By: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
 xen/arch/x86/io_apic.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/io_apic.c b/xen/arch/x86/io_apic.c
index b48a642465..d73108558e 100644
--- a/xen/arch/x86/io_apic.c
+++ b/xen/arch/x86/io_apic.c
@@ -1692,7 +1692,8 @@ static void cf_check mask_and_ack_level_ioapic_irq(struct 
irq_desc *desc)
        !io_apic_level_ack_pending(desc->irq))
         move_masked_irq(desc);
 
-    if ( !(v & (1 << (i & 0x1f))) ) {
+    if ( !(v & (1U << (i & 0x1f))) )
+    {
         spin_lock(&ioapic_lock);
         __edge_IO_APIC_irq(desc->irq);
         __level_IO_APIC_irq(desc->irq);
@@ -1756,7 +1757,8 @@ static void cf_check end_level_ioapic_irq_new(struct 
irq_desc *desc, u8 vector)
          !io_apic_level_ack_pending(desc->irq) )
         move_native_irq(desc);
 
-    if (!(v & (1 << (i & 0x1f)))) {
+    if ( !(v & (1U << (i & 0x1f))) )
+    {
         spin_lock(&ioapic_lock);
         __mask_IO_APIC_irq(desc->irq);
         __edge_IO_APIC_irq(desc->irq);
--
generated by git-patchbot for /home/xen/git/xen.git#master