Add dirty ring test if kernel supports it.  Add the dirty ring parameter on
source should be mostly enough, but let's change the dest too to make them
match always.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 tests/qtest/migration-test.c | 58 ++++++++++++++++++++++++++++++++++--
 1 file changed, 55 insertions(+), 3 deletions(-)

diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
index d9225f58d4d..9ef6b471353 100644
--- a/tests/qtest/migration-test.c
+++ b/tests/qtest/migration-test.c
@@ -27,6 +27,10 @@
 #include "migration-helpers.h"
 #include "tests/migration/migration-test.h"
 
+#if defined(__linux__)
+#include "linux/kvm.h"
+#endif
+
 /* TODO actually test the results and get rid of this */
 #define qtest_qmp_discard_response(...) qobject_unref(qtest_qmp(__VA_ARGS__))
 
@@ -467,6 +471,8 @@ typedef struct {
     bool use_shmem;
     /* only launch the target process */
     bool only_target;
+    /* Use dirty ring if true; dirty logging otherwise */
+    bool use_dirty_ring;
     char *opts_source;
     char *opts_target;
 } MigrateStart;
@@ -573,11 +579,13 @@ static int test_migrate_start(QTestState **from, QTestState **to,
         shmem_opts = g_strdup("");
     }
 
-    cmd_source = g_strdup_printf("-accel kvm -accel tcg%s%s "
+    cmd_source = g_strdup_printf("-accel kvm%s -accel tcg%s%s "
                                  "-name source,debug-threads=on "
                                  "-m %s "
                                  "-serial file:%s/src_serial "
                                  "%s %s %s %s",
+                                 args->use_dirty_ring ?
+                                 ",dirty-ring-size=4096" : "",
                                  machine_opts ? " -machine " : "",
                                  machine_opts ? machine_opts : "",
                                  memory_size, tmpfs,
@@ -587,12 +595,14 @@ static int test_migrate_start(QTestState **from, QTestState **to,
         *from = qtest_init(cmd_source);
     }
 
-    cmd_target = g_strdup_printf("-accel kvm -accel tcg%s%s "
+    cmd_target = g_strdup_printf("-accel kvm%s -accel tcg%s%s "
                                  "-name target,debug-threads=on "
                                  "-m %s "
                                  "-serial file:%s/dest_serial "
                                  "-incoming %s "
                                  "%s %s %s %s",
+                                 args->use_dirty_ring ?
+                                 ",dirty-ring-size=4096" : "",
                                  machine_opts ? " -machine " : "",
                                  machine_opts ? machine_opts : "",
                                  memory_size, tmpfs, uri,
@@ -785,12 +795,14 @@ static void test_baddest(void)
     test_migrate_end(from, to, false);
 }
 
-static void test_precopy_unix(void)
+static void test_precopy_unix_common(bool dirty_ring)
 {
     g_autofree char *uri = g_strdup_printf("unix:%s/migsocket", tmpfs);
     MigrateStart *args = migrate_start_new();
     QTestState *from, *to;
 
+    args->use_dirty_ring = dirty_ring;
+
     if (test_migrate_start(&from, &to, uri, args)) {
         return;
     }
@@ -825,6 +837,18 @@ static void test_precopy_unix(void)
     test_migrate_end(from, to, true);
 }
 
+static void test_precopy_unix(void)
+{
+    /* Using default dirty logging */
+    test_precopy_unix_common(false);
+}
+
+static void test_precopy_unix_dirty_ring(void)
+{
+    /* Using dirty ring tracking */
+    test_precopy_unix_common(true);
+}
+
 #if 0
 /* Currently upset on aarch64 TCG */
 static void test_ignore_shared(void)
@@ -1369,6 +1393,29 @@ static void test_multifd_tcp_cancel(void)
     test_migrate_end(from, to2, true);
 }
 
+static bool kvm_dirty_ring_supported(void)
+{
+#if defined(__linux__)
+    int ret, kvm_fd = open("/dev/kvm", O_RDONLY);
+
+    if (kvm_fd < 0) {
+        return false;
+    }
+
+    ret = ioctl(kvm_fd, KVM_CHECK_EXTENSION, KVM_CAP_DIRTY_LOG_RING);
+    close(kvm_fd);
+
+    /* We test with 4096 slots */
+    if (ret < 4096) {
+        return false;
+    }
+
+    return true;
+#else
+    return false;
+#endif
+}
+
 int main(int argc, char **argv)
 {
     char template[] = "/tmp/migration-test-XXXXXX";
@@ -1438,6 +1485,11 @@ int main(int argc, char **argv)
     qtest_add_func("/migration/multifd/tcp/zstd", test_multifd_tcp_zstd);
 #endif
 
+    if (kvm_dirty_ring_supported()) {
+        qtest_add_func("/migration/dirty_ring",
+                       test_precopy_unix_dirty_ring);
+    }
+
     ret = g_test_run();
 
     g_assert_cmpint(ret, ==, 0);
-- 
2.31.1

Peter Xu <peterx@redhat.com> wrote:
> Add dirty ring test if kernel supports it.  Add the dirty ring parameter on
> source should be mostly enough, but let's change the dest too to make them
> match always.
>
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>

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

Why we check with 4096 and not whatever the kernel returs?

So ....

> @@ -467,6 +471,8 @@ typedef struct {
>      bool use_shmem;
>      /* only launch the target process */
>      bool only_target;
> +    /* Use dirty ring if true; dirty logging otherwise */
> +    bool use_dirty_ring;

make this an int

>      char *opts_source;
>      char *opts_target;
>  } MigrateStart;
> @@ -573,11 +579,13 @@ static int test_migrate_start(QTestState **from, QTestState **to,
>          shmem_opts = g_strdup("");
>      }
>  
> -    cmd_source = g_strdup_printf("-accel kvm -accel tcg%s%s "
> +    cmd_source = g_strdup_printf("-accel kvm%s -accel tcg%s%s "
>                                   "-name source,debug-threads=on "
>                                   "-m %s "
>                                   "-serial file:%s/src_serial "
>                                   "%s %s %s %s",
> +                                 args->use_dirty_ring ?
> +                                 ",dirty-ring-size=4096" : "",

check if it is > 0 here and otherwise pass it

>                                   machine_opts ? " -machine " : "",
>                                   machine_opts ? machine_opts : "",
>                                   memory_size, tmpfs,
> @@ -587,12 +595,14 @@ static int test_migrate_start(QTestState **from, QTestState **to,
>          *from = qtest_init(cmd_source);

> +static bool kvm_dirty_ring_supported(void)
> +{
> +#if defined(__linux__)
> +    int ret, kvm_fd = open("/dev/kvm", O_RDONLY);
> +
> +    if (kvm_fd < 0) {
> +        return false;
> +    }
> +
> +    ret = ioctl(kvm_fd, KVM_CHECK_EXTENSION, KVM_CAP_DIRTY_LOG_RING);
> +    close(kvm_fd);
> +
> +    /* We test with 4096 slots */
> +    if (ret < 4096) {

And we return this value.

> +        return false;
> +    }
> +
> +    return true;
> +#else
> +    return false;
> +#endif
> +}

Mental note, don't we have a function inside tests/ that check if
a kvm feauture is there?

Quick check seems to imply no.

On the other hand, KVM_CHECK_EXTENSION is basically only used on
kvm-all.c

Later, Juan.

On Wed, Jun 16, 2021 at 02:55:55PM +0200, Juan Quintela wrote:
> Peter Xu <peterx@redhat.com> wrote:
> > Add dirty ring test if kernel supports it.  Add the dirty ring parameter on
> > source should be mostly enough, but let's change the dest too to make them
> > match always.
> >
> > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> 
> Reviewed-by: Juan Quintela <quintela@redhat.com>
> 
> Why we check with 4096 and not whatever the kernel returs?

Because the kernel returned value is the "maximum supported", while IMHO it's
better to test with some commonly used value (which should normally not the
maximum supported one; 4096 is suggested the default value to use so far in
e.g. qemu-options.hx).

> 
> So ....
> 
> > @@ -467,6 +471,8 @@ typedef struct {
> >      bool use_shmem;
> >      /* only launch the target process */
> >      bool only_target;
> > +    /* Use dirty ring if true; dirty logging otherwise */
> > +    bool use_dirty_ring;
> 
> make this an int
> 
> >      char *opts_source;
> >      char *opts_target;
> >  } MigrateStart;
> > @@ -573,11 +579,13 @@ static int test_migrate_start(QTestState **from, QTestState **to,
> >          shmem_opts = g_strdup("");
> >      }
> >  
> > -    cmd_source = g_strdup_printf("-accel kvm -accel tcg%s%s "
> > +    cmd_source = g_strdup_printf("-accel kvm%s -accel tcg%s%s "
> >                                   "-name source,debug-threads=on "
> >                                   "-m %s "
> >                                   "-serial file:%s/src_serial "
> >                                   "%s %s %s %s",
> > +                                 args->use_dirty_ring ?
> > +                                 ",dirty-ring-size=4096" : "",
> 
> check if it is > 0 here and otherwise pass it
> 
> >                                   machine_opts ? " -machine " : "",
> >                                   machine_opts ? machine_opts : "",
> >                                   memory_size, tmpfs,
> > @@ -587,12 +595,14 @@ static int test_migrate_start(QTestState **from, QTestState **to,
> >          *from = qtest_init(cmd_source);
> 
> > +static bool kvm_dirty_ring_supported(void)
> > +{
> > +#if defined(__linux__)
> > +    int ret, kvm_fd = open("/dev/kvm", O_RDONLY);
> > +
> > +    if (kvm_fd < 0) {
> > +        return false;
> > +    }
> > +
> > +    ret = ioctl(kvm_fd, KVM_CHECK_EXTENSION, KVM_CAP_DIRTY_LOG_RING);
> > +    close(kvm_fd);
> > +
> > +    /* We test with 4096 slots */
> > +    if (ret < 4096) {
> 
> And we return this value.
> 
> > +        return false;
> > +    }
> > +
> > +    return true;
> > +#else
> > +    return false;
> > +#endif
> > +}
> 
> Mental note, don't we have a function inside tests/ that check if
> a kvm feauture is there?
> 
> Quick check seems to imply no.
> 
> On the other hand, KVM_CHECK_EXTENSION is basically only used on
> kvm-all.c

Yeah, seems not there yet..  So we don't have guarantee to run this new test
because normally the host kernel is unpredictable, but it'll run on more hosts
as time flies and as people upgrade the kernels, meanwhile it can be run by
anyone who wants to regress dirty ring with a known new host kernel (so
e.g. for migration pull we can run migration-test with any host kernel newer
than 5.11+ and also run with root to cover all test cases there).

Thanks,

-- 
Peter Xu

On 6/15/21 7:55 AM, Peter Xu wrote:
> Add dirty ring test if kernel supports it.  Add the dirty ring parameter on
> source should be mostly enough, but let's change the dest too to make them
> match always.
> 
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>   tests/qtest/migration-test.c | 58 ++++++++++++++++++++++++++++++++++--
>   1 file changed, 55 insertions(+), 3 deletions(-)
> 
> diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
> index d9225f58d4d..9ef6b471353 100644
> --- a/tests/qtest/migration-test.c
> +++ b/tests/qtest/migration-test.c
> @@ -27,6 +27,10 @@
>   #include "migration-helpers.h"
>   #include "tests/migration/migration-test.h"
>   
> +#if defined(__linux__)
> +#include "linux/kvm.h"
> +#endif

This breaks the build for hosts that do not support kvm, e.g. sparc:


[2/3] Compiling C object tests/qtest/migration-test.p/migration-test.c.o
FAILED: tests/qtest/migration-test.p/migration-test.c.o
cc -Itests/qtest/migration-test.p -Itests/qtest -I../qemu/tests/qtest -I. -Iqapi -Itrace 
-Iui -Iui/shader -I/usr/include/glib-2.0 -I/usr/lib/sparc64-linux-gnu/glib-2.0/include 
-fdiagnostics-color=auto -pipe -Wall -Winvalid-pch -Werror -std=gnu11 -O2 -g -isystem 
/home/rth/qemu/qemu/linux-headers -isystem linux-headers -iquote . -iquote 
/home/rth/qemu/qemu -iquote /home/rth/qemu/qemu/include -iquote 
/home/rth/qemu/qemu/disas/libvixl -iquote /home/rth/qemu/qemu/tcg/sparc -pthread 
-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -m64 -mcpu=ultrasparc -D_GNU_SOURCE 
-D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wundef 
-Wwrite-strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv 
-Wold-style-declaration -Wold-style-definition -Wtype-limits -Wformat-security 
-Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body -Wnested-externs -Wendif-labels 
-Wexpansion-to-defined -Wimplicit-fallthrough=2 -Wno-missing-include-dirs 
-Wno-shift-negative-value -Wno-psabi -fPIE -MD -MQ 
tests/qtest/migration-test.p/migration-test.c.o -MF 
tests/qtest/migration-test.p/migration-test.c.o.d -o 
tests/qtest/migration-test.p/migration-test.c.o -c ../qemu/tests/qtest/migration-test.c
In file included from ../qemu/tests/qtest/migration-test.c:31:
/home/rth/qemu/qemu/linux-headers/linux/kvm.h:15:10: fatal error: asm/kvm.h: No such file 
or directory
    15 | #include <asm/kvm.h>
       |          ^~~~~~~~~~~
compilation terminated.


r~

On Wed, Jul 28, 2021 at 09:37:48AM -1000, Richard Henderson wrote:
> On 6/15/21 7:55 AM, Peter Xu wrote:
> > Add dirty ring test if kernel supports it.  Add the dirty ring parameter on
> > source should be mostly enough, but let's change the dest too to make them
> > match always.
> > 
> > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> > ---
> >   tests/qtest/migration-test.c | 58 ++++++++++++++++++++++++++++++++++--
> >   1 file changed, 55 insertions(+), 3 deletions(-)
> > 
> > diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
> > index d9225f58d4d..9ef6b471353 100644
> > --- a/tests/qtest/migration-test.c
> > +++ b/tests/qtest/migration-test.c
> > @@ -27,6 +27,10 @@
> >   #include "migration-helpers.h"
> >   #include "tests/migration/migration-test.h"
> > +#if defined(__linux__)
> > +#include "linux/kvm.h"
> > +#endif
> 
> This breaks the build for hosts that do not support kvm, e.g. sparc:
> 
> 
> [2/3] Compiling C object tests/qtest/migration-test.p/migration-test.c.o
> FAILED: tests/qtest/migration-test.p/migration-test.c.o
> cc -Itests/qtest/migration-test.p -Itests/qtest -I../qemu/tests/qtest -I.
> -Iqapi -Itrace -Iui -Iui/shader -I/usr/include/glib-2.0
> -I/usr/lib/sparc64-linux-gnu/glib-2.0/include -fdiagnostics-color=auto -pipe
> -Wall -Winvalid-pch -Werror -std=gnu11 -O2 -g -isystem
> /home/rth/qemu/qemu/linux-headers -isystem linux-headers -iquote . -iquote
> /home/rth/qemu/qemu -iquote /home/rth/qemu/qemu/include -iquote
> /home/rth/qemu/qemu/disas/libvixl -iquote /home/rth/qemu/qemu/tcg/sparc
> -pthread -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -m64 -mcpu=ultrasparc
> -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes
> -Wredundant-decls -Wundef -Wwrite-strings -Wmissing-prototypes
> -fno-strict-aliasing -fno-common -fwrapv -Wold-style-declaration
> -Wold-style-definition -Wtype-limits -Wformat-security -Wformat-y2k
> -Winit-self -Wignored-qualifiers -Wempty-body -Wnested-externs
> -Wendif-labels -Wexpansion-to-defined -Wimplicit-fallthrough=2
> -Wno-missing-include-dirs -Wno-shift-negative-value -Wno-psabi -fPIE -MD -MQ
> tests/qtest/migration-test.p/migration-test.c.o -MF
> tests/qtest/migration-test.p/migration-test.c.o.d -o
> tests/qtest/migration-test.p/migration-test.c.o -c
> ../qemu/tests/qtest/migration-test.c
> In file included from ../qemu/tests/qtest/migration-test.c:31:
> /home/rth/qemu/qemu/linux-headers/linux/kvm.h:15:10: fatal error: asm/kvm.h:
> No such file or directory
>    15 | #include <asm/kvm.h>
>       |          ^~~~~~~~~~~
> compilation terminated.

Hi, Richard,

Sorry for that.  It's very weird that linux/kvm.h exists for all archs while
it's not conditionally including asm/kvm.h only for the 5 supported archs, so
any user app trying to include linux/kvm.h will fail for the rest.

(while all references needed in this test is actually KVM_CHECK_EXTENSION,
 KVM_CAP_DIRTY_LOG_RING and both of them exist in linux/kvm.h not the asm one)

A quick fix attached; would that work for us?

Thanks,

-- 
Peter Xu
From 888ab46c44284738d222edc87e9fc86a49ae2f51 Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Wed, 28 Jul 2021 16:32:00 -0400
Subject: [PATCH] tests: Fix migration-test build failure for sparc

Even if <linux/kvm.h> seems to exist for all archs on linux, however including
it with __linux__ defined seems to be not working yet as it'll try to include
asm/kvm.h and that can be missing for archs that do not support kvm.

To fix this (instead of any attempt to fix linux headers..), we can mark the
header to be x86_64 only, because it's so far only service for adding the kvm
dirty ring test.

Reported-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 tests/qtest/migration-test.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
index 1e8b7784ef..cc5e83d98a 100644
--- a/tests/qtest/migration-test.c
+++ b/tests/qtest/migration-test.c
@@ -27,7 +27,8 @@
 #include "migration-helpers.h"
 #include "tests/migration/migration-test.h"
 
-#if defined(__linux__)
+/* For dirty ring test; so far only x86_64 is supported */
+#if defined(__linux__) && defined(HOST_X86_64)
 #include "linux/kvm.h"
 #endif
 
@@ -1395,7 +1396,7 @@ static void test_multifd_tcp_cancel(void)
 
 static bool kvm_dirty_ring_supported(void)
 {
-#if defined(__linux__)
+#if defined(__linux__) && defined(HOST_X86_64)
     int ret, kvm_fd = open("/dev/kvm", O_RDONLY);
 
     if (kvm_fd < 0) {
-- 
2.31.1

On 7/28/21 10:37 AM, Peter Xu wrote:
> A quick fix attached; would that work for us?

Looks plausible, though perhaps just as easy to list the 5 platforms as just the one:

#if defined(__linux__) && \
     (defined(HOST_X86_64) || \
      defined(HOST_S390X) || \
      ...)
# define HAVE_KVM
#endif


r~

On Wed, Jul 28, 2021 at 11:11:30AM -1000, Richard Henderson wrote:
> On 7/28/21 10:37 AM, Peter Xu wrote:
> > A quick fix attached; would that work for us?
> 
> Looks plausible, though perhaps just as easy to list the 5 platforms as just the one:
> 
> #if defined(__linux__) && \
>     (defined(HOST_X86_64) || \
>      defined(HOST_S390X) || \
>      ...)
> # define HAVE_KVM
> #endif

That looks good to me, especially for the long term to identify whether kvm is
with us, but for the short-term I hope I can still use the (literally :)
simpler patch as attached so hopefully that'll be more welcomed as rc2+
material..

Note again that the kvm.h inclusion is only for kvm dirty ring test in
migration-test so far, meanwhile that's only supported on x86_64, so we won't
lose anything on the rest 4 archs.

Thanks!

-- 
Peter Xu