The pci.0 bus on a pc machine has 32 slots.

For q35 machines, we don't expect devices to be plugged into
pcie.0 directly, so technically we could have a very large
number of slots by adding many pcie-root-ports, but even in
this scenario 32 is a reasonable number.

Signed-off-by: Andrea Bolognani <abologna(a)redhat.com>
---
 qrap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/qrap.c b/qrap.c
index 287198e..2443fa3 100644
--- a/qrap.c
+++ b/qrap.c
@@ -89,13 +89,13 @@ static const struct pci_dev {
 		"pc-q35", "virtio-net-pci",
 		"bus=pci.", ",addr=0x0",
 		"\"bus\":\"pci.",
",\"addr\":\"0x0\"",
-		3, /* 2: hotplug bus */ 16
+		3, /* 2: hotplug bus */ 31
 	},
 	{
 		"pc-", "virtio-net-pci",
 		"bus=pci.0,addr=0x", "",
 		"\"bus\":\"pci.0\",\"addr=0x", "",
-		2, /* 1: ISA bridge */ 16
+		2, /* 1: ISA bridge */ 31
 	},
 	{
 		"s390-ccw", "virtio-net-ccw",
-- 
2.39.2

The JSON version of the template is incorrect, making qrap
completely unusable when JSON arguments are used together
with the pc machine type.

Fixes: b944ca185587 ("qrap: Support JSON syntax for -device")
Signed-off-by: Andrea Bolognani <abologna(a)redhat.com>
---
 qrap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qrap.c b/qrap.c
index 2443fa3..5c18cec 100644
--- a/qrap.c
+++ b/qrap.c
@@ -94,7 +94,7 @@ static const struct pci_dev {
 	{
 		"pc-", "virtio-net-pci",
 		"bus=pci.0,addr=0x", "",
-		"\"bus\":\"pci.0\",\"addr=0x", "",
+		"\"bus\":\"pci.0\",\"addr\":\"0x",
"",
 		2, /* 1: ISA bridge */ 31
 	},
 	{
-- 
2.39.2

When JSON support was introduced, the drop_args array has
not been updated accordingly.

Fixes: b944ca185587 ("qrap: Support JSON syntax for -device")
Signed-off-by: Andrea Bolognani <abologna(a)redhat.com>
---
 qrap.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/qrap.c b/qrap.c
index 5c18cec..3077944 100644
--- a/qrap.c
+++ b/qrap.c
@@ -57,10 +57,15 @@ static const struct drop_arg {
 	{ "-netdev",	NULL },
 	{ "-net",	NULL },
 	{ "-device",	"virtio-net-pci," },
+	{ "-device",	"{\"driver\":\"virtio-net-pci\","
},
 	{ "-device",	"virtio-net-ccw," },
+	{ "-device",	"{\"driver\":\"virtio-net-ccw\","
},
 	{ "-device",	"e1000," },
+	{ "-device",	"{\"driver\":\"e1000\"," },
 	{ "-device",	"e1000e," },
+	{ "-device",	"{\"driver\":\"e1000e\"," },
 	{ "-device",	"rtl8139," },
+	{ "-device",	"{\"driver\":\"rtl8139\"," },
 	{ 0 },
 };
 
-- 
2.39.2

For pc machines, devices are placed directly on pci.0 with
addresses like

  bus=pci.0,addr=0xa

and in this case the existing code works correctly.

For q35 machines, however, a separate PCI bus is created for
each devices using a pcie-root-port, and the resulting
addresses look like

  bus=pci.9,addr=0x0

In this case, we need to treat PCI addresses as decimal, not
hexadecimal, both when parsing and generating them.

This issue has gone unnoticed for a long time because it only
shows up when enough PCI devices are present: for small
numbers, decimal and hexadecimal overlap, masking the issue.

Reported-by: Alona Paz <alkaplan(a)redhat.com>
Fixes: 5307faa05997 ("qrap: Strip network devices from command line, set them up
according to machine")
Signed-off-by: Andrea Bolognani <abologna(a)redhat.com>
---
 qrap.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/qrap.c b/qrap.c
index 3077944..27c12ed 100644
--- a/qrap.c
+++ b/qrap.c
@@ -77,6 +77,7 @@ static const struct drop_arg {
  * @template_post:	Suffix for device specification (last part of address)
  * @template_json:		Device prefix for when JSON is used
  * @template_json_post:	Device suffix for when JSON is used
+ * @base:		Base used for PCI addresses
  * @first:		First usable PCI address
  * @last:		Last usable PCI address
  */
@@ -87,6 +88,7 @@ static const struct pci_dev {
 	char *template_post;
 	char *template_json;
 	char *template_json_post;
+	int base;
 	int first;
 	int last;
 } pci_devs[] = {
@@ -94,19 +96,19 @@ static const struct pci_dev {
 		"pc-q35", "virtio-net-pci",
 		"bus=pci.", ",addr=0x0",
 		"\"bus\":\"pci.",
",\"addr\":\"0x0\"",
-		3, /* 2: hotplug bus */ 31
+		10, 3, /* 2: hotplug bus */ 31
 	},
 	{
 		"pc-", "virtio-net-pci",
 		"bus=pci.0,addr=0x", "",
 		"\"bus\":\"pci.0\",\"addr\":\"0x",
"",
-		2, /* 1: ISA bridge */ 31
+		16, 2, /* 1: ISA bridge */ 31
 	},
 	{
 		"s390-ccw", "virtio-net-ccw",
 		"devno=fe.0.", "",
 		"\"devno\":\"fe.0.", "",
-		1, 16
+		16, 1, 16
 	},
 	{ 0 },
 };
@@ -264,7 +266,7 @@ int main(int argc, char **argv)
 			if (template) {
 				long n;
 
-				n = strtol(p + strlen(template), NULL, 16);
+				n = strtol(p + strlen(template), NULL, dev->base);
 				if (!errno)
 					addr_map |= (1 << n);
 			}
@@ -285,13 +287,25 @@ int main(int argc, char **argv)
 	if (has_dev) {
 		qemu_argv[qemu_argc++] = "-device";
 		if (!has_json) {
-			snprintf(dev_str, ARG_MAX,
-			         "%s,%s%x%s,netdev=hostnet0,x-txburst=4096",
-			         dev->name, dev->template, i, dev->template_post);
+			if (dev->base == 16) {
+				snprintf(dev_str, ARG_MAX,
+				         "%s,%s%x%s,netdev=hostnet0,x-txburst=4096",
+				         dev->name, dev->template, i, dev->template_post);
+			} else if (dev->base == 10) {
+				snprintf(dev_str, ARG_MAX,
+				         "%s,%s%d%s,netdev=hostnet0,x-txburst=4096",
+				         dev->name, dev->template, i, dev->template_post);
+			}
 		} else {
-			snprintf(dev_str, ARG_MAX,
-			        
"{\"driver\":\"%s\",%s%x\"%s,\"netdev\":\"hostnet0\",\"x-txburst\":4096}",
-			         dev->name, dev->template_json, i, dev->template_json_post);
+			if (dev->base == 16) {
+				snprintf(dev_str, ARG_MAX,
+				        
"{\"driver\":\"%s\",%s%x\"%s,\"netdev\":\"hostnet0\",\"x-txburst\":4096}",
+				         dev->name, dev->template_json, i, dev->template_json_post);
+			} else if (dev->base == 10) {
+				snprintf(dev_str, ARG_MAX,
+				        
"{\"driver\":\"%s\",%s%d\"%s,\"netdev\":\"hostnet0\",\"x-txburst\":4096}",
+				         dev->name, dev->template_json, i, dev->template_json_post);
+			}
 		}
 		qemu_argv[qemu_argc++] = dev_str;
 	}
-- 
2.39.2

While generating -device as JSON when JSON is in use is
mandatory, because not doing so can often prevent the VM from
starting up, using JSON for -netdev simply makes things a bit
nicer. No reason not to do it, though.

Signed-off-by: Andrea Bolognani <abologna(a)redhat.com>
---
 qrap.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/qrap.c b/qrap.c
index 27c12ed..d0e2fb2 100644
--- a/qrap.c
+++ b/qrap.c
@@ -311,7 +311,11 @@ int main(int argc, char **argv)
 	}
 
 	qemu_argv[qemu_argc++] = "-netdev";
-	qemu_argv[qemu_argc++] = "socket,fd=" STR(DEFAULT_FD)
",id=hostnet0";
+	if (!has_json) {
+		qemu_argv[qemu_argc++] = "socket,fd=" STR(DEFAULT_FD)
",id=hostnet0";
+	} else {
+		qemu_argv[qemu_argc++] =
"{\"type\":\"socket\",\"fd\":\""
STR(DEFAULT_FD) "\",\"id\":\"hostnet0\"}";
+	}
 	qemu_argv[qemu_argc] = NULL;
 
 valid_args:
-- 
2.39.2

On Fri, Feb 24, 2023 at 07:49:44PM +0100, Andrea Bolognani wrote:
...
  Andrea Bolognani (5):
   qrap: Fix limits for PCI addresses
   qrap: Fix support for pc machines
   qrap: Drop args in JSON format
   qrap: Introduce machine-specific PCI address base
   qrap: Generate -netdev as JSON

  qrap.c | 47 +++++++++++++++++++++++++++++++++++------------
  1 file changed, 35 insertions(+), 12 deletions(-) 
Some information about testing.

In order to convince myself that the changes I was working on were
correct, I have created a few quick and dirty test scripts. You can
find them here:

  https://gitlab.com/abologna/passt/-/commits/qrap-tests

The commit contains a few YAML files:

  vmi-small-q35-passt.yaml # q35 VM with few devices
  vmi-small-pc-passt.yaml  #  pc VM with few devices
  vmi-big-q35-passt.yaml   # q35 VM with many devices
  vmi-big-pc-passt.yaml    #  pc VM with many devices

Each one of those, fed into KubeVirt, results in qrap being called
with a bunch of command line arguments. These are normally passed to
the actual QEMU binary, but in my case I've hacked qrap so that
they're simply printed out.

For each of the scenarios, there are three files:

  vm.in  # arguments passed to qrap
  vm.exp # arguments generated by the current version of qrap
  vm.sh  # test script

Running vm.sh results in qrap being called with the same arguments
contained in vm.in (but quoted for shell consumption), with the
output collected into the temporary file vm.out. This file is then
compared with both vm.in (to highlight changes made by qrap) and with
vm.exp (to highlight changes in behavior compared to the current
version of qrap).


Running these tests before applying my patches should result in
vm.out being identical to vm.ext whereas, after my patches have been
applied, the following important changes will be visible:

  --- pc-small.exp	2023-02-24 20:11:14.559711296 +0100
  +++ pc-small.out	2023-02-24 20:26:53.557307727 +0100
  @@ -75,6 +75,6 @@
   -msg
   timestamp=on
   -device
  -virtio-net-pci,bus=pci.0,addr=0x2,netdev=hostnet0,x-txburst=4096
 
+{"driver":"virtio-net-pci","bus":"pci.0","addr":"0x8","netdev":"hostnet0","x-txburst":4096}

(addresses of other devices are now parsed correctly, so qrap's
interface will be assigned to slot 8, which is available, instead of
slot 2, which isn't)

  --- q35-big.exp	2023-02-24 20:11:14.560711288 +0100
  +++ q35-big.out	2023-02-24 20:27:20.632094269 +0100
  @@ -159,6 +159,6 @@
   -msg
   timestamp=on
   -device
 
-{"driver":"virtio-net-pci","bus":"pci.a","addr":"0x0","netdev":"hostnet0","x-txburst":4096}
 
+{"driver":"virtio-net-pci","bus":"pci.15","addr":"0x0","netdev":"hostnet0","x-txburst":4096}

(pci.15 is correctly identified as the bus where qrap's interface
should be placed instead of the non-existing pci.a bus)

  --- pc-big.exp	2023-02-24 20:11:14.559711296 +0100
  +++ pc-big.out	2023-02-24 20:27:37.124964240 +0100
  @@ -129,6 +129,6 @@
   -msg
   timestamp=on
   -device
  -virtio-net-pci,bus=pci.0,addr=0x2,netdev=hostnet0,x-txburst=4096
 
+{"driver":"virtio-net-pci","bus":"pci.0","addr":"0x11","netdev":"hostnet0","x-txburst":4096}

(again, an available slot will be picked)

Note how the q35-small test sees no differences. That's the one
scenario that was already working, so the lack of changes there is a
very good thing :)


In addition to these crude test scripts, I've also made a custom
RPM build of passt with these patches applied and integrated it into
KubeVirt. Using it, I was able to successfully submit all the YAML
files mentioned earlier and get working VMs, with functional network
connection, as a result.

I also ran the passt tests from KubeVirt's own functional test suite,
and they all passed except for one. That one's about IPv6
connectivity, and I think the lack of IPv6 connectivity in my own
machine / network is to blame for the failure. This specific test
fails with the non-patched version of passt too, further validating
this theory.

-- 
Andrea Bolognani / Red Hat / Virtualization