[pve-devel] [PATCH qemu] add patches to fix regression with LSI SCSI controller

[Fiona Ebner <f.ebner@proxmox.com>]

The patch 0008-memory-prevent-dma-reentracy-issues.patch introduced a
regression for the LSI SCSI controller leading to boot failures [0],
because, in its current form, it relies on reentrancy for a particular
ram_io region.

[0]: https://forum.proxmox.com/threads/123843

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---

Needs these two patches first (for the numbering in the series file):
https://lists.proxmox.com/pipermail/pve-devel/2023-March/056110.html

 ...isabling-re-entrancy-checking-per-MR.patch | 38 +++++++++++++++++++
 ...le-reentrancy-detection-for-script-R.patch | 33 ++++++++++++++++
 debian/patches/series                         |  2 +
 3 files changed, 73 insertions(+)
 create mode 100644 debian/patches/extra/0021-memory-Allow-disabling-re-entrancy-checking-per-MR.patch
 create mode 100644 debian/patches/extra/0022-lsi53c895a-disable-reentrancy-detection-for-script-R.patch

diff --git a/debian/patches/extra/0021-memory-Allow-disabling-re-entrancy-checking-per-MR.patch b/debian/patches/extra/0021-memory-Allow-disabling-re-entrancy-checking-per-MR.patch
new file mode 100644
index 0000000..3d5c267
--- /dev/null
+++ b/debian/patches/extra/0021-memory-Allow-disabling-re-entrancy-checking-per-MR.patch
@@ -0,0 +1,38 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Alexander Bulekov <alxndr@bu.edu>
+Date: Mon, 13 Mar 2023 04:24:16 -0400
+Subject: [PATCH] memory: Allow disabling re-entrancy checking per-MR
+
+Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
+---
+ include/exec/memory.h | 3 +++
+ softmmu/memory.c      | 2 +-
+ 2 files changed, 4 insertions(+), 1 deletion(-)
+
+diff --git a/include/exec/memory.h b/include/exec/memory.h
+index 91f8a2395a..d7268d9f39 100644
+--- a/include/exec/memory.h
++++ b/include/exec/memory.h
+@@ -765,6 +765,9 @@ struct MemoryRegion {
+     unsigned ioeventfd_nb;
+     MemoryRegionIoeventfd *ioeventfds;
+     RamDiscardManager *rdm; /* Only for RAM */
++
++    /* For devices designed to perform re-entrant IO into their own IO MRs */
++    bool disable_reentrancy_guard;
+ };
+ 
+ struct IOMMUMemoryRegion {
+diff --git a/softmmu/memory.c b/softmmu/memory.c
+index 7dcb3347aa..2b46714191 100644
+--- a/softmmu/memory.c
++++ b/softmmu/memory.c
+@@ -544,7 +544,7 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
+     }
+ 
+     /* Do not allow more than one simultanous access to a device's IO Regions */
+-    if (mr->owner &&
++    if (mr->owner && !mr->disable_reentrancy_guard &&
+         !mr->ram_device && !mr->ram && !mr->rom_device && !mr->readonly) {
+         dev = (DeviceState *) object_dynamic_cast(mr->owner, TYPE_DEVICE);
+         if (dev) {
diff --git a/debian/patches/extra/0022-lsi53c895a-disable-reentrancy-detection-for-script-R.patch b/debian/patches/extra/0022-lsi53c895a-disable-reentrancy-detection-for-script-R.patch
new file mode 100644
index 0000000..a4ed0ee
--- /dev/null
+++ b/debian/patches/extra/0022-lsi53c895a-disable-reentrancy-detection-for-script-R.patch
@@ -0,0 +1,33 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Alexander Bulekov <alxndr@bu.edu>
+Date: Mon, 13 Mar 2023 04:24:17 -0400
+Subject: [PATCH] lsi53c895a: disable reentrancy detection for script RAM
+
+As the code is designed to use the memory APIs to access the script ram,
+disable reentrancy checks for the pseudo-RAM ram_io MemoryRegion.
+
+In the future, ram_io may be converted from an IO to a proper RAM MemoryRegion.
+
+Reported-by: Fiona Ebner <f.ebner@proxmox.com>
+Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
+---
+ hw/scsi/lsi53c895a.c | 6 ++++++
+ 1 file changed, 6 insertions(+)
+
+diff --git a/hw/scsi/lsi53c895a.c b/hw/scsi/lsi53c895a.c
+index 50979640c3..894b9311ac 100644
+--- a/hw/scsi/lsi53c895a.c
++++ b/hw/scsi/lsi53c895a.c
+@@ -2302,6 +2302,12 @@ static void lsi_scsi_realize(PCIDevice *dev, Error **errp)
+     memory_region_init_io(&s->io_io, OBJECT(s), &lsi_io_ops, s,
+                           "lsi-io", 256);
+ 
++    /*
++     * Since we use the address-space API to interact with ram_io, disable the
++     * re-entrancy guard.
++     */
++    s->ram_io.disable_reentrancy_guard = true;
++
+     address_space_init(&s->pci_io_as, pci_address_space_io(dev), "lsi-pci-io");
+     qdev_init_gpio_out(d, &s->ext_irq, 1);
+ 
diff --git a/debian/patches/series b/debian/patches/series
index ba3279e..681b57d 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -18,6 +18,8 @@ extra/0017-vhost-avoid-a-potential-use-of-an-uninitialized-vari.patch
 extra/0018-chardev-char-socket-set-s-listener-NULL-in-char_sock.patch
 extra/0019-intel-iommu-fail-MAP-notifier-without-caching-mode.patch
 extra/0020-intel-iommu-fail-DEVIOTLB_UNMAP-without-dt-mode.patch
+extra/0021-memory-Allow-disabling-re-entrancy-checking-per-MR.patch
+extra/0022-lsi53c895a-disable-reentrancy-detection-for-script-R.patch
 bitmap-mirror/0001-drive-mirror-add-support-for-sync-bitmap-mode-never.patch
 bitmap-mirror/0002-drive-mirror-add-support-for-conditional-and-always-.patch
 bitmap-mirror/0003-mirror-add-check-for-bitmap-mode-without-bitmap.patch
-- 
2.30.2