[PATCH v2 6/9] qapi: Generalize command policy checking

Markus Armbruster posted 9 patches 4 years, 3 months ago
There is a newer version of this series
[PATCH v2 6/9] qapi: Generalize command policy checking
Posted by Markus Armbruster 4 years, 3 months ago
The code to check command policy can see special feature flag
'deprecated' as command flag QCO_DEPRECATED.  I want to make feature
flag 'unstable' visible there as well, so I can add policy for it.

To let me make it visible, add member @special_features (a bitset of
QapiSpecialFeature) to QmpCommand, and adjust the generator to pass it
through qmp_register_command().  Then replace "QCO_DEPRECATED in
@flags" by QAPI_DEPRECATED in @special_features", and drop
QCO_DEPRECATED.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: John Snow <jsnow@redhat.com>
---
 include/qapi/qmp/dispatch.h          | 5 +++--
 monitor/misc.c                       | 6 ++++--
 qapi/qmp-dispatch.c                  | 2 +-
 qapi/qmp-registry.c                  | 4 +++-
 storage-daemon/qemu-storage-daemon.c | 3 ++-
 scripts/qapi/commands.py             | 9 ++++-----
 6 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/include/qapi/qmp/dispatch.h b/include/qapi/qmp/dispatch.h
index 0ce88200b9..1e4240fd0d 100644
--- a/include/qapi/qmp/dispatch.h
+++ b/include/qapi/qmp/dispatch.h
@@ -25,7 +25,6 @@ typedef enum QmpCommandOptions
     QCO_ALLOW_OOB             =  (1U << 1),
     QCO_ALLOW_PRECONFIG       =  (1U << 2),
     QCO_COROUTINE             =  (1U << 3),
-    QCO_DEPRECATED            =  (1U << 4),
 } QmpCommandOptions;
 
 typedef struct QmpCommand
@@ -34,6 +33,7 @@ typedef struct QmpCommand
     /* Runs in coroutine context if QCO_COROUTINE is set */
     QmpCommandFunc *fn;
     QmpCommandOptions options;
+    unsigned special_features;
     QTAILQ_ENTRY(QmpCommand) node;
     bool enabled;
     const char *disable_reason;
@@ -42,7 +42,8 @@ typedef struct QmpCommand
 typedef QTAILQ_HEAD(QmpCommandList, QmpCommand) QmpCommandList;
 
 void qmp_register_command(QmpCommandList *cmds, const char *name,
-                          QmpCommandFunc *fn, QmpCommandOptions options);
+                          QmpCommandFunc *fn, QmpCommandOptions options,
+                          unsigned special_features);
 const QmpCommand *qmp_find_command(const QmpCommandList *cmds,
                                    const char *name);
 void qmp_disable_command(QmpCommandList *cmds, const char *name,
diff --git a/monitor/misc.c b/monitor/misc.c
index 3556b177f6..c2d227a07c 100644
--- a/monitor/misc.c
+++ b/monitor/misc.c
@@ -230,11 +230,13 @@ static void monitor_init_qmp_commands(void)
 
     qmp_init_marshal(&qmp_commands);
 
-    qmp_register_command(&qmp_commands, "device_add", qmp_device_add, 0);
+    qmp_register_command(&qmp_commands, "device_add",
+                         qmp_device_add, 0, 0);
 
     QTAILQ_INIT(&qmp_cap_negotiation_commands);
     qmp_register_command(&qmp_cap_negotiation_commands, "qmp_capabilities",
-                         qmp_marshal_qmp_capabilities, QCO_ALLOW_PRECONFIG);
+                         qmp_marshal_qmp_capabilities,
+                         QCO_ALLOW_PRECONFIG, 0);
 }
 
 /* Set the current CPU defined by the user. Callers must hold BQL. */
diff --git a/qapi/qmp-dispatch.c b/qapi/qmp-dispatch.c
index 7e943a0af5..8cca18c891 100644
--- a/qapi/qmp-dispatch.c
+++ b/qapi/qmp-dispatch.c
@@ -176,7 +176,7 @@ QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request,
                   "The command %s has not been found", command);
         goto out;
     }
-    if (cmd->options & QCO_DEPRECATED) {
+    if (cmd->special_features & 1u << QAPI_DEPRECATED) {
         switch (compat_policy.deprecated_input) {
         case COMPAT_POLICY_INPUT_ACCEPT:
             break;
diff --git a/qapi/qmp-registry.c b/qapi/qmp-registry.c
index f78c064aae..485bc5e6fc 100644
--- a/qapi/qmp-registry.c
+++ b/qapi/qmp-registry.c
@@ -16,7 +16,8 @@
 #include "qapi/qmp/dispatch.h"
 
 void qmp_register_command(QmpCommandList *cmds, const char *name,
-                          QmpCommandFunc *fn, QmpCommandOptions options)
+                          QmpCommandFunc *fn, QmpCommandOptions options,
+                          unsigned special_features)
 {
     QmpCommand *cmd = g_malloc0(sizeof(*cmd));
 
@@ -27,6 +28,7 @@ void qmp_register_command(QmpCommandList *cmds, const char *name,
     cmd->fn = fn;
     cmd->enabled = true;
     cmd->options = options;
+    cmd->special_features = special_features;
     QTAILQ_INSERT_TAIL(cmds, cmd, node);
 }
 
diff --git a/storage-daemon/qemu-storage-daemon.c b/storage-daemon/qemu-storage-daemon.c
index 10a1a33761..52cf17e8ac 100644
--- a/storage-daemon/qemu-storage-daemon.c
+++ b/storage-daemon/qemu-storage-daemon.c
@@ -146,7 +146,8 @@ static void init_qmp_commands(void)
 
     QTAILQ_INIT(&qmp_cap_negotiation_commands);
     qmp_register_command(&qmp_cap_negotiation_commands, "qmp_capabilities",
-                         qmp_marshal_qmp_capabilities, QCO_ALLOW_PRECONFIG);
+                         qmp_marshal_qmp_capabilities,
+                         QCO_ALLOW_PRECONFIG, 0);
 }
 
 static int getopt_set_loc(int argc, char **argv, const char *optstring,
diff --git a/scripts/qapi/commands.py b/scripts/qapi/commands.py
index c8a975528f..21001bbd6b 100644
--- a/scripts/qapi/commands.py
+++ b/scripts/qapi/commands.py
@@ -26,6 +26,7 @@
     QAPISchemaModularCVisitor,
     build_params,
     ifcontext,
+    gen_special_features,
 )
 from .schema import (
     QAPISchema,
@@ -217,9 +218,6 @@ def gen_register_command(name: str,
                          coroutine: bool) -> str:
     options = []
 
-    if 'deprecated' in [f.name for f in features]:
-        options += ['QCO_DEPRECATED']
-
     if not success_response:
         options += ['QCO_NO_SUCCESS_RESP']
     if allow_oob:
@@ -231,10 +229,11 @@ def gen_register_command(name: str,
 
     ret = mcgen('''
     qmp_register_command(cmds, "%(name)s",
-                         qmp_marshal_%(c_name)s, %(opts)s);
+                         qmp_marshal_%(c_name)s, %(opts)s, %(feats)s);
 ''',
                 name=name, c_name=c_name(name),
-                opts=' | '.join(options) or 0)
+                opts=' | '.join(options) or 0,
+                feats=gen_special_features(features))
     return ret
 
 
-- 
2.31.1

Re: [PATCH v2 6/9] qapi: Generalize command policy checking
Posted by Juan Quintela 4 years, 3 months ago
Markus Armbruster <armbru@redhat.com> wrote:
> The code to check command policy can see special feature flag
> 'deprecated' as command flag QCO_DEPRECATED.  I want to make feature
> flag 'unstable' visible there as well, so I can add policy for it.
>
> To let me make it visible, add member @special_features (a bitset of
> QapiSpecialFeature) to QmpCommand, and adjust the generator to pass it
> through qmp_register_command().  Then replace "QCO_DEPRECATED in
> @flags" by QAPI_DEPRECATED in @special_features", and drop
> QCO_DEPRECATED.
>
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Acked-by: John Snow <jsnow@redhat.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>


Re: [PATCH v2 6/9] qapi: Generalize command policy checking
Posted by Eric Blake 4 years, 3 months ago
On Thu, Oct 28, 2021 at 12:25:17PM +0200, Markus Armbruster wrote:
> The code to check command policy can see special feature flag
> 'deprecated' as command flag QCO_DEPRECATED.  I want to make feature
> flag 'unstable' visible there as well, so I can add policy for it.
> 
> To let me make it visible, add member @special_features (a bitset of
> QapiSpecialFeature) to QmpCommand, and adjust the generator to pass it
> through qmp_register_command().  Then replace "QCO_DEPRECATED in
> @flags" by QAPI_DEPRECATED in @special_features", and drop
> QCO_DEPRECATED.
> 
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Acked-by: John Snow <jsnow@redhat.com>
> ---

> +++ b/qapi/qmp-dispatch.c
> @@ -176,7 +176,7 @@ QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request,
>                    "The command %s has not been found", command);
>          goto out;
>      }
> -    if (cmd->options & QCO_DEPRECATED) {
> +    if (cmd->special_features & 1u << QAPI_DEPRECATED) {

I admit having to check the C operator precedence table when reading
this (<< is higher than &); if writing it myself, I would probably
have used explicit () to avoid reviewer confusion, but what you have
is correct.  (After grepping for ' & 1.*<<' and ' & (1.*<<', it looks
like authors using explicit precedence happens more often, but that
there are other instances in the code base relying on implicit
precedence.)

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

Re: [PATCH v2 6/9] qapi: Generalize command policy checking
Posted by Philippe Mathieu-Daudé 4 years, 3 months ago
On 10/29/21 17:28, Eric Blake wrote:
> On Thu, Oct 28, 2021 at 12:25:17PM +0200, Markus Armbruster wrote:
>> The code to check command policy can see special feature flag
>> 'deprecated' as command flag QCO_DEPRECATED.  I want to make feature
>> flag 'unstable' visible there as well, so I can add policy for it.
>>
>> To let me make it visible, add member @special_features (a bitset of
>> QapiSpecialFeature) to QmpCommand, and adjust the generator to pass it
>> through qmp_register_command().  Then replace "QCO_DEPRECATED in
>> @flags" by QAPI_DEPRECATED in @special_features", and drop
>> QCO_DEPRECATED.
>>
>> Signed-off-by: Markus Armbruster <armbru@redhat.com>
>> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>> Acked-by: John Snow <jsnow@redhat.com>
>> ---
> 
>> +++ b/qapi/qmp-dispatch.c
>> @@ -176,7 +176,7 @@ QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request,
>>                    "The command %s has not been found", command);
>>          goto out;
>>      }
>> -    if (cmd->options & QCO_DEPRECATED) {
>> +    if (cmd->special_features & 1u << QAPI_DEPRECATED) {
> 
> I admit having to check the C operator precedence table when reading

This doesn't seem a good use of (y)our time. Using a pair of parenthesis
is simpler.

I expect in a not far future that compilers emit a warning for this.

> this (<< is higher than &); if writing it myself, I would probably
> have used explicit () to avoid reviewer confusion, but what you have
> is correct.  (After grepping for ' & 1.*<<' and ' & (1.*<<', it looks
> like authors using explicit precedence happens more often, but that
> there are other instances in the code base relying on implicit
> precedence.)

$ git grep -E ' & [0-9a-zA-Z_]+ <<'
hw/dma/pl330.c:997:    if (~ch->parent->inten & ch->parent->ev_status &
1 << ev_id) {
hw/dma/xlnx-zynq-devcfg.c:198:        if (s->regs[R_LOCK] & 1 << i) {
hw/intc/grlib_irqmp.c:144:        if (s->broadcast & 1 << irq) {
hw/net/fsl_etsec/rings.c:491:    if (etsec->regs[RSTAT].value & 1 << (23
- ring_nbr)) {
hw/net/virtio-net.c:748:            (n->host_features & 1ULL <<
VIRTIO_NET_F_MTU)) {
hw/pci-host/mv64361.c:812:                if ((ch & 0xff << i) && !(val
& 0xff << i)) {
hw/pci-host/mv64361.c:858:        if (s->gpp_int_level && !(val & 0xff
<< b)) {
hw/ssi/xilinx_spi.c:123:        qemu_set_irq(s->cs_lines[i],
!(~s->regs[R_SPISSR] & 1 << i));
hw/ssi/xilinx_spips.c:441:            r[idx[!d]] |= x[idx[d]] & 1 <<
bit[d] ? 1 << bit[!d] : 0;
target/s390x/cpu_features.c:56:                if (init[i] & 1ULL << j) {
tests/qtest/bios-tables-test.c:209:    if (!(val & 1UL << 20 /*
HW_REDUCED_ACPI */)) {

Not that many.