[SeaBIOS] [PATCH v2] optionrom: disallow int19 redirect for pnp roms.

[Gerd Hoffmann]

Check whenever pnp roms attempt to redirect int19, and in case it does
log a message and undo the redirect.

A pnp rom should not need this, we have BEVs and BCVs for that.
Nevertheless there are roms in the wild which are redirecting int19.
At least some BIOS implementations for physical hardware have a config
option in the setup to allow/disallow int19 redirections, so just not
allowing this seems to be the way to deal with this situation.

Buglink: https://bugzilla.redhat.com//show_bug.cgi?id=1642135
Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
---
 src/optionroms.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/src/optionroms.c b/src/optionroms.c
index fc992f649f..e90900b790 100644
--- a/src/optionroms.c
+++ b/src/optionroms.c
@@ -8,6 +8,7 @@
 #include "bregs.h" // struct bregs
 #include "config.h" // CONFIG_*
 #include "farptr.h" // FLATPTR_TO_SEG
+#include "biosvar.h" // GET_IVT
 #include "hw/pci.h" // pci_config_readl
 #include "hw/pcidevice.h" // foreachpci
 #include "hw/pci_ids.h" // PCI_CLASS_DISPLAY_VGA
@@ -308,6 +309,24 @@ fail:
     return NULL;
 }
 
+static int boot_irq_captured(void)
+{
+    struct segoff_s current, seabios;
+
+    current = GET_IVT(0x19);
+    seabios = FUNC16(entry_19_official);
+    return ((current.seg != seabios.seg) ||
+            (current.offset != current.offset));
+}
+
+static void boot_irq_restore(void)
+{
+    struct segoff_s seabios;
+
+    seabios = FUNC16(entry_19_official);
+    SET_IVT(0x19, seabios);
+}
+
 // Attempt to map and initialize the option rom on a given PCI device.
 static void
 init_pcirom(struct pci_device *pci, int isvga, u64 *sources)
@@ -327,8 +346,18 @@ init_pcirom(struct pci_device *pci, int isvga, u64 *sources)
     if (! rom)
         // No ROM present.
         return;
+    int irq_was_captured = boot_irq_captured();
+    struct pnp_data *pnp = get_pnp_rom(rom);
     setRomSource(sources, rom, RS_PCIROM | (u32)pci);
     init_optionrom(rom, pci->bdf, isvga);
+    if (boot_irq_captured() && !irq_was_captured &&
+        !file && !isvga && pnp) {
+        // This PCI rom is misbehaving - recapture the boot irqs
+        char *desc = MAKE_FLATPTR(FLATPTR_TO_SEG(rom), pnp->productname);
+        dprintf(1, "PnP optionrom \"%s\" (bdf %pP) captured int19, restoring\n",
+                desc, pci);
+        boot_irq_restore();
+    }
 }
 
 
-- 
2.9.3