From c4466179f49742a22ba94ec0747ae153a00133cc Mon Sep 17 00:00:00 2001
From: Andrea Bolognani <abologna@redhat.com>
Date: Thu, 19 Apr 2018 17:55:41 +0200
Subject: [PATCH] conf: Add rom.enabled attribute for PCI devices

The attribute can be used to disable ROM loading completely
for a device.

This might be needed because, even when the guest is configured
such that the PCI ROM will not be loaded in the PCI BAR, some
hypervisors (eg. QEMU) might still make it available to the
guest in a form (eg. fw_cfg) that some firmwares (eg. SeaBIOS)
will consume, thus not achieving the desired result.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
---
 docs/formatdomain.html.in     |  6 ++++++
 docs/schemas/domaincommon.rng |  5 +++++
 src/conf/device_conf.h        |  1 +
 src/conf/domain_conf.c        | 25 ++++++++++++++++++++++++-
 4 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index ada0df227f..8e864f7113 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -4476,6 +4476,12 @@
         virtual function of an sr-iov capable ethernet device (which
         has no boot ROMs for the VFs).
         <span class="since">Since 0.9.10 (QEMU and KVM only)</span>.
+        The optional <code>enabled</code> attribute can be set to
+        <code>no</code> to disable PCI ROM loading completely for the device;
+        if PCI ROM loading is disabled through this attribute, attempts to
+        tweak the loading process further using the <code>bar</code> or
+        <code>file</code> attributes will be rejected.
+        <span class="since">Since 4.3.0 (QEMU and KVM only)</span>.
       </dd>
       <dt><code>address</code></dt>
       <dd>The <code>address</code> element for USB devices has a
diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index 4cab55f05d..3569b92127 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -5108,6 +5108,11 @@
 
   <define name="rom">
     <element name="rom">
+      <optional>
+        <attribute name="enabled">
+          <ref name="virYesNo"/>
+        </attribute>
+      </optional>
       <optional>
         <attribute name="bar">
           <ref name="virOnOff"/>
diff --git a/src/conf/device_conf.h b/src/conf/device_conf.h
index f87d6f1fc6..a31ce9c376 100644
--- a/src/conf/device_conf.h
+++ b/src/conf/device_conf.h
@@ -153,6 +153,7 @@ struct _virDomainDeviceInfo {
     } master;
     /* rombar and romfile are only used for pci hostdev and network
      * devices. */
+    int romenabled; /* enum virTristateBool */
     int rombar;         /* enum virTristateSwitch */
     char *romfile;
     /* bootIndex is only used for disk, network interface, hostdev
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 65b429460a..9f7dce1bed 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -6095,9 +6095,17 @@ virDomainDeviceInfoFormat(virBufferPtr buf,
     }
 
     if ((flags & VIR_DOMAIN_DEF_FORMAT_ALLOW_ROM) &&
-        (info->rombar != VIR_TRISTATE_SWITCH_ABSENT || info->romfile)) {
+        (info->romenabled != VIR_TRISTATE_BOOL_ABSENT ||
+         info->rombar != VIR_TRISTATE_SWITCH_ABSENT ||
+         info->romfile)) {
 
         virBufferAddLit(buf, "<rom");
+        if (info->romenabled != VIR_TRISTATE_BOOL_ABSENT) {
+            const char *romenabled = virTristateBoolTypeToString(info->romenabled);
+
+            if (romenabled)
+                virBufferAsprintf(buf, " enabled='%s'", romenabled);
+        }
         if (info->rombar != VIR_TRISTATE_SWITCH_ABSENT) {
             const char *rombar = virTristateSwitchTypeToString(info->rombar);
 
@@ -6738,6 +6746,7 @@ virDomainDeviceInfoParseXML(virDomainXMLOptionPtr xmlopt ATTRIBUTE_UNUSED,
     xmlNodePtr boot = NULL;
     xmlNodePtr rom = NULL;
     char *type = NULL;
+    char *romenabled = NULL;
     char *rombar = NULL;
     char *aliasStr = NULL;
     int ret = -1;
@@ -6791,6 +6800,12 @@ virDomainDeviceInfoParseXML(virDomainXMLOptionPtr xmlopt ATTRIBUTE_UNUSED,
     }
 
     if (rom) {
+        if ((romenabled = virXMLPropString(rom, "enabled")) &&
+            ((info->romenabled = virTristateBoolTypeFromString(romenabled)) <= 0)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("unknown rom enabled value '%s'"), romenabled);
+            goto cleanup;
+        }
         if ((rombar = virXMLPropString(rom, "bar")) &&
             ((info->rombar = virTristateSwitchTypeFromString(rombar)) <= 0)) {
             virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
@@ -6798,6 +6813,13 @@ virDomainDeviceInfoParseXML(virDomainXMLOptionPtr xmlopt ATTRIBUTE_UNUSED,
             goto cleanup;
         }
         info->romfile = virXMLPropString(rom, "file");
+
+        if (info->romenabled == VIR_TRISTATE_BOOL_NO &&
+            (info->rombar != VIR_TRISTATE_SWITCH_ABSENT || info->romfile)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("ROM tuning is not supported when ROM is disabled"));
+            goto cleanup;
+        }
     }
 
     if (address &&
@@ -6811,6 +6833,7 @@ virDomainDeviceInfoParseXML(virDomainXMLOptionPtr xmlopt ATTRIBUTE_UNUSED,
         virDomainDeviceInfoClear(info);
     VIR_FREE(type);
     VIR_FREE(rombar);
+    VIR_FREE(romenabled);
     VIR_FREE(aliasStr);
     return ret;
 }