From 47d027147694fde94dd73305ee53b6a136cbeced Mon Sep 17 00:00:00 2001
From: Jon Maloy <jmaloy@redhat.com>
Date: Tue, 9 May 2023 10:29:03 -0400
Subject: [PATCH 08/15] apic: disable reentrancy detection for apic-msi

RH-Author: Jon Maloy <jmaloy@redhat.com>
RH-MergeRequest: 277: memory: prevent dma-reentracy issues
RH-Bugzilla: 1999236
RH-Acked-by: Thomas Huth <thuth@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Commit: [8/12] 25c3cf99b00cd9adc10d6e7afa9c3e3b7da08de2 (redhat/rhel/src/qemu-kvm/jons-qemu-kvm-2)

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1999236
Upstream: Merged
CVE: CVE-2021-3750

commit 50795ee051a342c681a9b45671c552fbd6274db8
Author: Alexander Bulekov <alxndr@bu.edu>
Date:   Thu Apr 27 17:10:13 2023 -0400

    apic: disable reentrancy detection for apic-msi

    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>
    Message-Id: <20230427211013.2994127-9-alxndr@bu.edu>
    Signed-off-by: Thomas Huth <thuth@redhat.com>

Signed-off-by: Jon Maloy <jmaloy@redhat.com>
---
 hw/intc/apic.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/intc/apic.c b/hw/intc/apic.c
index 3df11c34d6..a7c2b301a8 100644
--- a/hw/intc/apic.c
+++ b/hw/intc/apic.c
@@ -883,6 +883,13 @@ 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;
 
-- 
2.37.3