[Qemu-devel] [PULL v2 0/9] Misc patches for QEMU 2.5-rc2

[Qemu-devel] [PULL v2 0/9] Misc patches for QEMU 2.5-rc2

[Paolo Bonzini]

The following changes since commit 4b6eda626fdb8bf90472c6868d502a2ac09abeeb:

  Merge remote-tracking branch 'remotes/lalrae/tags/mips-20151124' into staging (2015-11-24 17:05:06 +0000)

are available in the git repository at:

  git://github.com/bonzini/qemu.git tags/for-upstream

for you to fetch changes up to 5120901a378501403d5454b69cf43e666fc29d5b:

  target-i386: kvm: Print warning when clearing mcg_cap bits (2015-11-26 16:48:16 +0100)

----------------------------------------------------------------
Small patches, without the one that introduces -fwrapv.

----------------------------------------------------------------
Daniel P. Berrange (2):
      Revert "exec: silence hugetlbfs warning under qtest"
      exec: remove warning about mempath and hugetlbfs

Eduardo Habkost (3):
      target-i386: kvm: Abort if MCE bank count is not supported by host
      target-i386: kvm: Use env->mcg_cap when setting up MCE
      target-i386: kvm: Print warning when clearing mcg_cap bits

Eugene (jno) Dvurechenski (1):
      virtio-scsi: don't crash without a valid device

Paolo Bonzini (2):
      MAINTAINERS: Update TCG CPU cores section
      target-sparc: fix 32-bit truncation in fpackfix

Wen Congyang (1):
      call bdrv_drain_all() even if the vm is stopped

 MAINTAINERS               | 17 +++++++++++++----
 cpus.c                    |  2 ++
 exec.c                    |  6 ------
 hw/scsi/virtio-scsi.c     |  2 +-
 target-i386/cpu.h         |  2 ++
 target-i386/kvm.c         | 22 ++++++++++++++--------
 target-sparc/vis_helper.c |  2 +-
 vl.c                      | 28 ++++++++++++++--------------
 8 files changed, 47 insertions(+), 34 deletions(-)
-- 
2.5.0

[Qemu-devel] [PULL 1/9] MAINTAINERS: Update TCG CPU cores section

[Paolo Bonzini]

These are the people that I think have been touching it lately
or reviewing patches.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 MAINTAINERS | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index 28f0139..bb1f3e4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -62,14 +62,22 @@ Guest CPU cores (TCG):
 ----------------------
 Overall
 L: qemu-devel@nongnu.org
-S: Odd fixes
+M: Paolo Bonzini <pbonzini@redhat.com>
+M: Peter Crosthwaite <crosthwaite.peter@gmail.com>
+M: Richard Henderson <rth@twiddle.net>
+S: Maintained
 F: cpu-exec.c
+F: cpu-exec-common.c
+F: cpus.c
 F: cputlb.c
+F: exec.c
 F: softmmu_template.h
-F: translate-all.c
-F: include/exec/cpu_ldst.h
-F: include/exec/cpu_ldst_template.h
+F: translate-all.*
+F: translate-common.c
+F: include/exec/cpu*.h
+F: include/exec/exec-all.h
 F: include/exec/helper*.h
+F: include/exec/tb-hash.h
 
 Alpha
 M: Richard Henderson <rth@twiddle.net>
@@ -1042,6 +1050,7 @@ S: Supported
 F: include/exec/ioport.h
 F: ioport.c
 F: include/exec/memory.h
+F: include/exec/ram_addr.h
 F: memory.c
 F: include/exec/memory-internal.h
 F: exec.c
-- 
2.5.0

[Qemu-devel] [PULL 2/9] call bdrv_drain_all() even if the vm is stopped

[Paolo Bonzini]

From: Wen Congyang <wency@cn.fujitsu.com>

There are still I/O operations when the vm is stopped. For example,
stop the vm, and do block migration. In this case, we don't drain all
I/O operation, and may meet the following problem:

qemu-system-x86_64: migration/block.c:731: block_save_complete: Assertion `block_mig_state.submitted == 0' failed.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Message-Id: <564EE92E.4070701@cn.fujitsu.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 cpus.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/cpus.c b/cpus.c
index 877bd70..43676fa 100644
--- a/cpus.c
+++ b/cpus.c
@@ -1415,6 +1415,8 @@ int vm_stop_force_state(RunState state)
         return vm_stop(state);
     } else {
         runstate_set(state);
+
+        bdrv_drain_all();
         /* Make sure to return an error if the flush in a previous vm_stop()
          * failed. */
         return bdrv_flush_all();
-- 
2.5.0

[Qemu-devel] [PULL 3/9] Revert "exec: silence hugetlbfs warning under qtest"

[Paolo Bonzini]

From: "Daniel P. Berrange" <berrange@redhat.com>

This reverts commit 1c7ba94a184df1eddd589d5400d879568d3e5d08.

That commit changed QEMU initialization order from

 - object-initial, chardev, qtest, object-late

to

 - chardev, qtest, object-initial, object-late

This breaks chardev setups which need to rely on objects
having been created. For example, when chardevs use TLS
encryption in the future, they need to have tls credential
objects created first.

This revert, restores the ordering introduced in

  commit f08f9271bfe3f19a5eb3d7a2f48532065304d5c8
  Author: Daniel P. Berrange <berrange@redhat.com>
  Date:   Wed May 13 17:14:04 2015 +0100

    vl: Create (most) objects before creating chardev backends

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1448448749-1332-2-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 exec.c |  5 +----
 vl.c   | 28 ++++++++++++++--------------
 2 files changed, 15 insertions(+), 18 deletions(-)

diff --git a/exec.c b/exec.c
index acbd4a2..b09f18b 100644
--- a/exec.c
+++ b/exec.c
@@ -51,7 +51,6 @@
 #include "qemu/main-loop.h"
 #include "translate-all.h"
 #include "sysemu/replay.h"
-#include "sysemu/qtest.h"
 
 #include "exec/memory-internal.h"
 #include "exec/ram_addr.h"
@@ -1197,10 +1196,8 @@ static long gethugepagesize(const char *path, Error **errp)
         return 0;
     }
 
-    if (!qtest_driver() &&
-        fs.f_type != HUGETLBFS_MAGIC) {
+    if (fs.f_type != HUGETLBFS_MAGIC)
         fprintf(stderr, "Warning: path not on HugeTLBFS: %s\n", path);
-    }
 
     return fs.f_bsize;
 }
diff --git a/vl.c b/vl.c
index 525929b..4211ff1 100644
--- a/vl.c
+++ b/vl.c
@@ -4291,26 +4291,17 @@ int main(int argc, char **argv, char **envp)
     page_size_init();
     socket_init();
 
-    if (qemu_opts_foreach(qemu_find_opts("chardev"),
-                          chardev_init_func, NULL, NULL)) {
-        exit(1);
-    }
-
-    if (qtest_chrdev) {
-        Error *local_err = NULL;
-        qtest_init(qtest_chrdev, qtest_log, &local_err);
-        if (local_err) {
-            error_report_err(local_err);
-            exit(1);
-        }
-    }
-
     if (qemu_opts_foreach(qemu_find_opts("object"),
                           object_create,
                           object_create_initial, NULL)) {
         exit(1);
     }
 
+    if (qemu_opts_foreach(qemu_find_opts("chardev"),
+                          chardev_init_func, NULL, NULL)) {
+        exit(1);
+    }
+
 #ifdef CONFIG_VIRTFS
     if (qemu_opts_foreach(qemu_find_opts("fsdev"),
                           fsdev_init_func, NULL, NULL)) {
@@ -4337,6 +4328,15 @@ int main(int argc, char **argv, char **envp)
 
     configure_accelerator(current_machine);
 
+    if (qtest_chrdev) {
+        Error *local_err = NULL;
+        qtest_init(qtest_chrdev, qtest_log, &local_err);
+        if (local_err) {
+            error_report_err(local_err);
+            exit(1);
+        }
+    }
+
     machine_opts = qemu_get_machine_opts();
     kernel_filename = qemu_opt_get(machine_opts, "kernel");
     initrd_filename = qemu_opt_get(machine_opts, "initrd");
-- 
2.5.0

[Qemu-devel] [PULL 4/9] exec: remove warning about mempath and hugetlbfs

[Paolo Bonzini]

From: "Daniel P. Berrange" <berrange@redhat.com>

The gethugepagesize() method in exec.c printed a warning if
the file path for "-mem-path" or "-object memory-backend-file"
was not on a hugetlbfs filesystem. This warning is bogus, because
QEMU functions perfectly well with the path on a regular tmpfs
filesystem. Use of hugetlbfs vs tmpfs is a choice for the management
application or end user to make as best fits their needs. As such it
is inappropriate for QEMU to have an opinion on whether the user's
choice is right or wrong in this case.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1448448749-1332-3-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 exec.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/exec.c b/exec.c
index b09f18b..de1cf19 100644
--- a/exec.c
+++ b/exec.c
@@ -1196,9 +1196,6 @@ static long gethugepagesize(const char *path, Error **errp)
         return 0;
     }
 
-    if (fs.f_type != HUGETLBFS_MAGIC)
-        fprintf(stderr, "Warning: path not on HugeTLBFS: %s\n", path);
-
     return fs.f_bsize;
 }
 
-- 
2.5.0

[Qemu-devel] [PULL 5/9] target-sparc: fix 32-bit truncation in fpackfix

[Paolo Bonzini]

This is reported by Coverity.  The algorithm description at
ftp://ftp.icm.edu.pl/packages/ggi/doc/hw/sparc/Sparc.pdf suggests
that the 32-bit parts of rs2, after the left shift, is treated
as a 64-bit integer.  Bits 32 and above are used to do the
saturating truncation.

Message-Id: <1446473134-4330-1-git-send-email-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target-sparc/vis_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target-sparc/vis_helper.c b/target-sparc/vis_helper.c
index 383cc8b..45fc7db 100644
--- a/target-sparc/vis_helper.c
+++ b/target-sparc/vis_helper.c
@@ -447,7 +447,7 @@ uint32_t helper_fpackfix(uint64_t gsr, uint64_t rs2)
     for (word = 0; word < 2; word++) {
         uint32_t val;
         int32_t src = rs2 >> (word * 32);
-        int64_t scaled = src << scale;
+        int64_t scaled = (int64_t)src << scale;
         int64_t from_fixed = scaled >> 16;
 
         val = (from_fixed < -32768 ? -32768 :
-- 
2.5.0

[Qemu-devel] [PULL 6/9] virtio-scsi: don't crash without a valid device

[Paolo Bonzini]

From: "Eugene (jno) Dvurechenski" <jno@linux.vnet.ibm.com>

Make sure that we actually have a device when checking the aio
context. Otherwise guests could trigger QEMU crashes.

Signed-off-by: "Eugene (jno) Dvurechenski" <jno@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Message-Id: <1448549135-6582-2-git-send-email-jno@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/scsi/virtio-scsi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 7655401..3a4f520 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -250,7 +250,7 @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
     int target;
     int ret = 0;
 
-    if (s->dataplane_started) {
+    if (s->dataplane_started && d) {
         assert(blk_get_aio_context(d->conf.blk) == s->ctx);
     }
     /* Here VIRTIO_SCSI_S_OK means "FUNCTION COMPLETE".  */
-- 
2.5.0

[Qemu-devel] [PULL 7/9] target-i386: kvm: Abort if MCE bank count is not supported by host

[Paolo Bonzini]

From: Eduardo Habkost <ehabkost@redhat.com>

Instead of silently changing the number of banks in mcg_cap based
on kvm_get_mce_cap_supported(), abort initialization if the host
doesn't support MCE_BANKS_DEF banks.

Note that MCE_BANKS_DEF was always 10 since it was introduced in
QEMU, and Linux always returned 32 at KVM_CAP_MCE since
KVM_CAP_MCE was introduced, so no behavior is being changed and
the error can't be triggered by any Linux version. The point of
the new check is to ensure we won't silently change the bank
count if we change MCE_BANKS_DEF or make the bank count
configurable in the future.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
[Avoid Yoda condition and \n at end of error_report. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1448471956-66873-8-git-send-email-pbonzini@redhat.com>
---
 target-i386/kvm.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 2a9953b..93d1f5e 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -784,11 +784,14 @@ int kvm_arch_init_vcpu(CPUState *cs)
             return ret;
         }
 
-        if (banks > MCE_BANKS_DEF) {
-            banks = MCE_BANKS_DEF;
+        if (banks < MCE_BANKS_DEF) {
+            error_report("kvm: Unsupported MCE bank count (QEMU = %d, KVM = %d)",
+                         MCE_BANKS_DEF, banks);
+            return -ENOTSUP;
         }
+
         mcg_cap &= MCE_CAP_DEF;
-        mcg_cap |= banks;
+        mcg_cap |= MCE_BANKS_DEF;
         ret = kvm_vcpu_ioctl(cs, KVM_X86_SETUP_MCE, &mcg_cap);
         if (ret < 0) {
             fprintf(stderr, "KVM_X86_SETUP_MCE: %s", strerror(-ret));
-- 
2.5.0

[Qemu-devel] [PULL 8/9] target-i386: kvm: Use env->mcg_cap when setting up MCE

[Paolo Bonzini]

From: Eduardo Habkost <ehabkost@redhat.com>

When setting up MCE, instead of using the MCE_*_DEF macros
directly, just filter the existing env->mcg_cap value.

As env->mcg_cap is already initialized as
MCE_CAP_DEF|MCE_BANKS_DEF at target-i386/cpu.c:mce_init(), this
doesn't change any behavior. But it will allow us to change
mce_init() in the future, to implement different defaults
depending on CPU model, machine-type or command-line parameters.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1448471956-66873-9-git-send-email-pbonzini@redhat.com>
---
 target-i386/cpu.h |  2 ++
 target-i386/kvm.c | 11 ++++-------
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index fc4a605..84edfd0 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -286,6 +286,8 @@
 #define MCE_CAP_DEF     (MCG_CTL_P|MCG_SER_P)
 #define MCE_BANKS_DEF   10
 
+#define MCG_CAP_BANKS_MASK 0xff
+
 #define MCG_STATUS_RIPV (1ULL<<0)   /* restart ip valid */
 #define MCG_STATUS_EIPV (1ULL<<1)   /* ip points to correct instruction */
 #define MCG_STATUS_MCIP (1ULL<<2)   /* machine check in progress */
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 93d1f5e..90bd447 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -784,21 +784,18 @@ int kvm_arch_init_vcpu(CPUState *cs)
             return ret;
         }
 
-        if (banks < MCE_BANKS_DEF) {
+        if (banks < (env->mcg_cap & MCG_CAP_BANKS_MASK)) {
             error_report("kvm: Unsupported MCE bank count (QEMU = %d, KVM = %d)",
-                         MCE_BANKS_DEF, banks);
+                         (int)(env->mcg_cap & MCG_CAP_BANKS_MASK), banks);
             return -ENOTSUP;
         }
 
-        mcg_cap &= MCE_CAP_DEF;
-        mcg_cap |= MCE_BANKS_DEF;
-        ret = kvm_vcpu_ioctl(cs, KVM_X86_SETUP_MCE, &mcg_cap);
+        env->mcg_cap &= mcg_cap | MCG_CAP_BANKS_MASK;
+        ret = kvm_vcpu_ioctl(cs, KVM_X86_SETUP_MCE, &env->mcg_cap);
         if (ret < 0) {
             fprintf(stderr, "KVM_X86_SETUP_MCE: %s", strerror(-ret));
             return ret;
         }
-
-        env->mcg_cap = mcg_cap;
     }
 
     qemu_add_vm_change_state_handler(cpu_update_state, env);
-- 
2.5.0

[Qemu-devel] [PULL 9/9] target-i386: kvm: Print warning when clearing mcg_cap bits

[Paolo Bonzini]

From: Eduardo Habkost <ehabkost@redhat.com>

Instead of silently clearing mcg_cap bits when the host doesn't
support them, print a warning when doing that.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
[Avoid \n at end of error_report. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1448471956-66873-10-git-send-email-pbonzini@redhat.com>
---
 target-i386/kvm.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 90bd447..6dc9846 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -774,7 +774,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
         && (env->features[FEAT_1_EDX] & (CPUID_MCE | CPUID_MCA)) ==
            (CPUID_MCE | CPUID_MCA)
         && kvm_check_extension(cs->kvm_state, KVM_CAP_MCE) > 0) {
-        uint64_t mcg_cap;
+        uint64_t mcg_cap, unsupported_caps;
         int banks;
         int ret;
 
@@ -790,6 +790,12 @@ int kvm_arch_init_vcpu(CPUState *cs)
             return -ENOTSUP;
         }
 
+        unsupported_caps = env->mcg_cap & ~(mcg_cap | MCG_CAP_BANKS_MASK);
+        if (unsupported_caps) {
+            error_report("warning: Unsupported MCG_CAP bits: 0x%" PRIx64,
+                         unsupported_caps);
+        }
+
         env->mcg_cap &= mcg_cap | MCG_CAP_BANKS_MASK;
         ret = kvm_vcpu_ioctl(cs, KVM_X86_SETUP_MCE, &env->mcg_cap);
         if (ret < 0) {
-- 
2.5.0

Re: [Qemu-devel] [PULL v2 0/9] Misc patches for QEMU 2.5-rc2

[Peter Maydell]

On 26 November 2015 at 15:52, Paolo Bonzini <pbonzini@redhat.com> wrote:
> The following changes since commit 4b6eda626fdb8bf90472c6868d502a2ac09abeeb:
>
>   Merge remote-tracking branch 'remotes/lalrae/tags/mips-20151124' into staging (2015-11-24 17:05:06 +0000)
>
> are available in the git repository at:
>
>   git://github.com/bonzini/qemu.git tags/for-upstream
>
> for you to fetch changes up to 5120901a378501403d5454b69cf43e666fc29d5b:
>
>   target-i386: kvm: Print warning when clearing mcg_cap bits (2015-11-26 16:48:16 +0100)
>
> ----------------------------------------------------------------
> Small patches, without the one that introduces -fwrapv.
>
> ----------------------------------------------------------------
> Daniel P. Berrange (2):
>       Revert "exec: silence hugetlbfs warning under qtest"
>       exec: remove warning about mempath and hugetlbfs
>
> Eduardo Habkost (3):
>       target-i386: kvm: Abort if MCE bank count is not supported by host
>       target-i386: kvm: Use env->mcg_cap when setting up MCE
>       target-i386: kvm: Print warning when clearing mcg_cap bits
>
> Eugene (jno) Dvurechenski (1):
>       virtio-scsi: don't crash without a valid device
>
> Paolo Bonzini (2):
>       MAINTAINERS: Update TCG CPU cores section
>       target-sparc: fix 32-bit truncation in fpackfix
>
> Wen Congyang (1):
>       call bdrv_drain_all() even if the vm is stopped
>

Applied, thanks.

-- PMM

[Qemu-devel] [PULL 0/9] Misc patches for QEMU 2.5-rc2 (2015-11-25)

[Paolo Bonzini]

The following changes since commit 4b6eda626fdb8bf90472c6868d502a2ac09abeeb:

  Merge remote-tracking branch 'remotes/lalrae/tags/mips-20151124' into staging (2015-11-24 17:05:06 +0000)

are available in the git repository at:


  git://github.com/bonzini/qemu.git tags/for-upstream

for you to fetch changes up to 6ac504d20a0967da06caadf595388f753908328a:

  target-i386: kvm: Print warning when clearing mcg_cap bits (2015-11-25 17:48:46 +0100)

----------------------------------------------------------------
Small patches, most notably the introduction of -fwrapv.

----------------------------------------------------------------
Daniel P. Berrange (2):
      Revert "exec: silence hugetlbfs warning under qtest"
      exec: remove warning about mempath and hugetlbfs

Eduardo Habkost (3):
      target-i386: kvm: Abort if MCE bank count is not supported by host
      target-i386: kvm: Use env->mcg_cap when setting up MCE
      target-i386: kvm: Print warning when clearing mcg_cap bits

Paolo Bonzini (3):
      MAINTAINERS: Update TCG CPU cores section
      QEMU does not care about left shifts of signed negative values
      target-sparc: fix 32-bit truncation in fpackfix

Wen Congyang (1):
      call bdrv_drain_all() even if the vm is stopped

 HACKING                   |  6 ++++++
 MAINTAINERS               | 17 +++++++++++++----
 configure                 |  4 ++--
 cpus.c                    |  2 ++
 exec.c                    |  6 ------
 target-i386/cpu.h         |  2 ++
 target-i386/kvm.c         | 22 ++++++++++++++--------
 target-sparc/vis_helper.c |  2 +-
 vl.c                      | 28 ++++++++++++++--------------
 9 files changed, 54 insertions(+), 35 deletions(-)
-- 
1.8.3.1

[Qemu-devel] [PULL 8/9] target-i386: kvm: Use env->mcg_cap when setting up MCE

[Paolo Bonzini]

From: Eduardo Habkost <ehabkost@redhat.com>

When setting up MCE, instead of using the MCE_*_DEF macros
directly, just filter the existing env->mcg_cap value.

As env->mcg_cap is already initialized as
MCE_CAP_DEF|MCE_BANKS_DEF at target-i386/cpu.c:mce_init(), this
doesn't change any behavior. But it will allow us to change
mce_init() in the future, to implement different defaults
depending on CPU model, machine-type or command-line parameters.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target-i386/cpu.h |  2 ++
 target-i386/kvm.c | 11 ++++-------
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index fc4a605..84edfd0 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -286,6 +286,8 @@
 #define MCE_CAP_DEF     (MCG_CTL_P|MCG_SER_P)
 #define MCE_BANKS_DEF   10
 
+#define MCG_CAP_BANKS_MASK 0xff
+
 #define MCG_STATUS_RIPV (1ULL<<0)   /* restart ip valid */
 #define MCG_STATUS_EIPV (1ULL<<1)   /* ip points to correct instruction */
 #define MCG_STATUS_MCIP (1ULL<<2)   /* machine check in progress */
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 93d1f5e..90bd447 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -784,21 +784,18 @@ int kvm_arch_init_vcpu(CPUState *cs)
             return ret;
         }
 
-        if (banks < MCE_BANKS_DEF) {
+        if (banks < (env->mcg_cap & MCG_CAP_BANKS_MASK)) {
             error_report("kvm: Unsupported MCE bank count (QEMU = %d, KVM = %d)",
-                         MCE_BANKS_DEF, banks);
+                         (int)(env->mcg_cap & MCG_CAP_BANKS_MASK), banks);
             return -ENOTSUP;
         }
 
-        mcg_cap &= MCE_CAP_DEF;
-        mcg_cap |= MCE_BANKS_DEF;
-        ret = kvm_vcpu_ioctl(cs, KVM_X86_SETUP_MCE, &mcg_cap);
+        env->mcg_cap &= mcg_cap | MCG_CAP_BANKS_MASK;
+        ret = kvm_vcpu_ioctl(cs, KVM_X86_SETUP_MCE, &env->mcg_cap);
         if (ret < 0) {
             fprintf(stderr, "KVM_X86_SETUP_MCE: %s", strerror(-ret));
             return ret;
         }
-
-        env->mcg_cap = mcg_cap;
     }
 
     qemu_add_vm_change_state_handler(cpu_update_state, env);
-- 
1.8.3.1