* [Qemu-devel] [PULL 0/1] i386: Don't automatically enable FEAT_KVM_HINTS bits
@ 2018-04-16 16:39 Eduardo Habkost
2018-04-16 16:39 ` [Qemu-devel] [PULL 1/1] " Eduardo Habkost
` (2 more replies)
0 siblings, 3 replies; 7+ messages in thread
From: Eduardo Habkost @ 2018-04-16 16:39 UTC (permalink / raw)
To: Peter Maydell
Cc: Paolo Bonzini, qemu-devel, Richard Henderson, Eduardo Habkost
Last remaining fix for -rc4.
The following changes since commit 042f6a31af3d38eefc6ec995cce1d762c41d4515:
Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2018-04-16' into staging (2018-04-16 15:30:54 +0100)
are available in the Git repository at:
git://github.com/ehabkost/qemu.git tags/x86-next-pull-request
for you to fetch changes up to 0d914f39a77954bf5472b16130aeefe573a068f5:
i386: Don't automatically enable FEAT_KVM_HINTS bits (2018-04-16 13:36:52 -0300)
----------------------------------------------------------------
i386: Don't automatically enable FEAT_KVM_HINTS bits
Bug fix for "-cpu host" with newer kernels.
----------------------------------------------------------------
Eduardo Habkost (1):
i386: Don't automatically enable FEAT_KVM_HINTS bits
target/i386/cpu.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--
2.14.3
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Qemu-devel] [PULL 1/1] i386: Don't automatically enable FEAT_KVM_HINTS bits
2018-04-16 16:39 [Qemu-devel] [PULL 0/1] i386: Don't automatically enable FEAT_KVM_HINTS bits Eduardo Habkost
@ 2018-04-16 16:39 ` Eduardo Habkost
2018-04-16 16:57 ` [Qemu-devel] [PULL 0/1] " Peter Maydell
2018-04-17 11:03 ` Peter Maydell
2 siblings, 0 replies; 7+ messages in thread
From: Eduardo Habkost @ 2018-04-16 16:39 UTC (permalink / raw)
To: Peter Maydell
Cc: Paolo Bonzini, qemu-devel, Richard Henderson, Eduardo Habkost
The assumption in the cpu->max_features code is that anything
enabled on GET_SUPPORTED_CPUID should be enabled on "-cpu host".
This shouldn't be the case for FEAT_KVM_HINTS.
This adds a new FeatureWordInfo::no_autoenable_flags field, that
can be used to prevent FEAT_KVM_HINTS bits to be enabled
automatically.
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20180410211534.26079-1-ehabkost@redhat.com>
Tested-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
target/i386/cpu.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 1a6b082b6f..a20fe26573 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -295,6 +295,8 @@ typedef struct FeatureWordInfo {
uint32_t tcg_features; /* Feature flags supported by TCG */
uint32_t unmigratable_flags; /* Feature flags known to be unmigratable */
uint32_t migratable_flags; /* Feature flags known to be migratable */
+ /* Features that shouldn't be auto-enabled by "-cpu host" */
+ uint32_t no_autoenable_flags;
} FeatureWordInfo;
static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
@@ -400,6 +402,11 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
},
.cpuid_eax = KVM_CPUID_FEATURES, .cpuid_reg = R_EDX,
.tcg_features = TCG_KVM_FEATURES,
+ /*
+ * KVM hints aren't auto-enabled by -cpu host, they need to be
+ * explicitly enabled in the command-line.
+ */
+ .no_autoenable_flags = ~0U,
},
[FEAT_HYPERV_EAX] = {
.feat_names = {
@@ -4062,7 +4069,8 @@ static void x86_cpu_expand_features(X86CPU *cpu, Error **errp)
*/
env->features[w] |=
x86_cpu_get_supported_feature_word(w, cpu->migratable) &
- ~env->user_features[w];
+ ~env->user_features[w] & \
+ ~feature_word_info[w].no_autoenable_flags;
}
}
--
2.14.3
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [Qemu-devel] [PULL 0/1] i386: Don't automatically enable FEAT_KVM_HINTS bits
2018-04-16 16:39 [Qemu-devel] [PULL 0/1] i386: Don't automatically enable FEAT_KVM_HINTS bits Eduardo Habkost
2018-04-16 16:39 ` [Qemu-devel] [PULL 1/1] " Eduardo Habkost
@ 2018-04-16 16:57 ` Peter Maydell
2018-04-16 17:42 ` Eduardo Habkost
2018-04-17 11:03 ` Peter Maydell
2 siblings, 1 reply; 7+ messages in thread
From: Peter Maydell @ 2018-04-16 16:57 UTC (permalink / raw)
To: Eduardo Habkost; +Cc: Paolo Bonzini, QEMU Developers, Richard Henderson
On 16 April 2018 at 17:39, Eduardo Habkost <ehabkost@redhat.com> wrote:
> Last remaining fix for -rc4.
>
> The following changes since commit 042f6a31af3d38eefc6ec995cce1d762c41d4515:
>
> Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2018-04-16' into staging (2018-04-16 15:30:54 +0100)
>
> are available in the Git repository at:
>
> git://github.com/ehabkost/qemu.git tags/x86-next-pull-request
>
> for you to fetch changes up to 0d914f39a77954bf5472b16130aeefe573a068f5:
>
> i386: Don't automatically enable FEAT_KVM_HINTS bits (2018-04-16 13:36:52 -0300)
>
> ----------------------------------------------------------------
> i386: Don't automatically enable FEAT_KVM_HINTS bits
>
> Bug fix for "-cpu host" with newer kernels.
>
> ----------------------------------------------------------------
Is this a regression since 2.11 ?
thanks
-- PMM
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Qemu-devel] [PULL 0/1] i386: Don't automatically enable FEAT_KVM_HINTS bits
2018-04-16 16:57 ` [Qemu-devel] [PULL 0/1] " Peter Maydell
@ 2018-04-16 17:42 ` Eduardo Habkost
2018-04-16 17:46 ` Eduardo Habkost
0 siblings, 1 reply; 7+ messages in thread
From: Eduardo Habkost @ 2018-04-16 17:42 UTC (permalink / raw)
To: Peter Maydell; +Cc: Paolo Bonzini, QEMU Developers, Richard Henderson
On Mon, Apr 16, 2018 at 05:57:35PM +0100, Peter Maydell wrote:
> On 16 April 2018 at 17:39, Eduardo Habkost <ehabkost@redhat.com> wrote:
> > Last remaining fix for -rc4.
> >
> > The following changes since commit 042f6a31af3d38eefc6ec995cce1d762c41d4515:
> >
> > Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2018-04-16' into staging (2018-04-16 15:30:54 +0100)
> >
> > are available in the Git repository at:
> >
> > git://github.com/ehabkost/qemu.git tags/x86-next-pull-request
> >
> > for you to fetch changes up to 0d914f39a77954bf5472b16130aeefe573a068f5:
> >
> > i386: Don't automatically enable FEAT_KVM_HINTS bits (2018-04-16 13:36:52 -0300)
> >
> > ----------------------------------------------------------------
> > i386: Don't automatically enable FEAT_KVM_HINTS bits
> >
> > Bug fix for "-cpu host" with newer kernels.
> >
> > ----------------------------------------------------------------
>
> Is this a regression since 2.11 ?
Yes.
--
Eduardo
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Qemu-devel] [PULL 0/1] i386: Don't automatically enable FEAT_KVM_HINTS bits
2018-04-16 17:42 ` Eduardo Habkost
@ 2018-04-16 17:46 ` Eduardo Habkost
2018-04-16 17:49 ` Peter Maydell
0 siblings, 1 reply; 7+ messages in thread
From: Eduardo Habkost @ 2018-04-16 17:46 UTC (permalink / raw)
To: Peter Maydell; +Cc: Paolo Bonzini, QEMU Developers, Richard Henderson
On Mon, Apr 16, 2018 at 02:42:52PM -0300, Eduardo Habkost wrote:
> On Mon, Apr 16, 2018 at 05:57:35PM +0100, Peter Maydell wrote:
> > On 16 April 2018 at 17:39, Eduardo Habkost <ehabkost@redhat.com> wrote:
> > > Last remaining fix for -rc4.
> > >
> > > The following changes since commit 042f6a31af3d38eefc6ec995cce1d762c41d4515:
> > >
> > > Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2018-04-16' into staging (2018-04-16 15:30:54 +0100)
> > >
> > > are available in the Git repository at:
> > >
> > > git://github.com/ehabkost/qemu.git tags/x86-next-pull-request
> > >
> > > for you to fetch changes up to 0d914f39a77954bf5472b16130aeefe573a068f5:
> > >
> > > i386: Don't automatically enable FEAT_KVM_HINTS bits (2018-04-16 13:36:52 -0300)
> > >
> > > ----------------------------------------------------------------
> > > i386: Don't automatically enable FEAT_KVM_HINTS bits
> > >
> > > Bug fix for "-cpu host" with newer kernels.
> > >
> > > ----------------------------------------------------------------
> >
> > Is this a regression since 2.11 ?
>
> Yes.
For reference, it was introduced by:
commit be7773268d98176489483a315d3e2323cb0615b9
Author: Wanpeng Li <wanpengli@tencent.com>
Date: Fri Feb 9 06:15:25 2018 -0800
target-i386: add KVM_HINTS_DEDICATED performance hint
Add KVM_HINTS_DEDICATED performance hint, guest checks this feature bit
to determine if they run on dedicated vCPUs, allowing optimizations such
as usage of qspinlocks.
Sorry for not including a "Fixes:" tag in the commit message. If
you think it's worth it, I can redo the pull request with it.
--
Eduardo
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Qemu-devel] [PULL 0/1] i386: Don't automatically enable FEAT_KVM_HINTS bits
2018-04-16 17:46 ` Eduardo Habkost
@ 2018-04-16 17:49 ` Peter Maydell
0 siblings, 0 replies; 7+ messages in thread
From: Peter Maydell @ 2018-04-16 17:49 UTC (permalink / raw)
To: Eduardo Habkost; +Cc: Paolo Bonzini, QEMU Developers, Richard Henderson
On 16 April 2018 at 18:46, Eduardo Habkost <ehabkost@redhat.com> wrote:
> On Mon, Apr 16, 2018 at 02:42:52PM -0300, Eduardo Habkost wrote:
>> On Mon, Apr 16, 2018 at 05:57:35PM +0100, Peter Maydell wrote:
>> > On 16 April 2018 at 17:39, Eduardo Habkost <ehabkost@redhat.com> wrote:
>> > > Last remaining fix for -rc4.
>> > >
>> > > The following changes since commit 042f6a31af3d38eefc6ec995cce1d762c41d4515:
>> > >
>> > > Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2018-04-16' into staging (2018-04-16 15:30:54 +0100)
>> > >
>> > > are available in the Git repository at:
>> > >
>> > > git://github.com/ehabkost/qemu.git tags/x86-next-pull-request
>> > >
>> > > for you to fetch changes up to 0d914f39a77954bf5472b16130aeefe573a068f5:
>> > >
>> > > i386: Don't automatically enable FEAT_KVM_HINTS bits (2018-04-16 13:36:52 -0300)
>> > >
>> > > ----------------------------------------------------------------
>> > > i386: Don't automatically enable FEAT_KVM_HINTS bits
>> > >
>> > > Bug fix for "-cpu host" with newer kernels.
>> > >
>> > > ----------------------------------------------------------------
>> >
>> > Is this a regression since 2.11 ?
>>
>> Yes.
>
> For reference, it was introduced by:
>
> commit be7773268d98176489483a315d3e2323cb0615b9
> Author: Wanpeng Li <wanpengli@tencent.com>
> Date: Fri Feb 9 06:15:25 2018 -0800
>
> target-i386: add KVM_HINTS_DEDICATED performance hint
>
> Add KVM_HINTS_DEDICATED performance hint, guest checks this feature bit
> to determine if they run on dedicated vCPUs, allowing optimizations such
> as usage of qspinlocks.
>
> Sorry for not including a "Fixes:" tag in the commit message. If
> you think it's worth it, I can redo the pull request with it.
No, that's fine. I'm just checking that we're all on the same page
about the level of fix that goes into a late-stage rc. Particularly
as we get past rc2 or so, it's definitely helpful to me if pull
request cover letters include justifications for why the changes
should go in.
thanks
-- PMM
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Qemu-devel] [PULL 0/1] i386: Don't automatically enable FEAT_KVM_HINTS bits
2018-04-16 16:39 [Qemu-devel] [PULL 0/1] i386: Don't automatically enable FEAT_KVM_HINTS bits Eduardo Habkost
2018-04-16 16:39 ` [Qemu-devel] [PULL 1/1] " Eduardo Habkost
2018-04-16 16:57 ` [Qemu-devel] [PULL 0/1] " Peter Maydell
@ 2018-04-17 11:03 ` Peter Maydell
2 siblings, 0 replies; 7+ messages in thread
From: Peter Maydell @ 2018-04-17 11:03 UTC (permalink / raw)
To: Eduardo Habkost; +Cc: Paolo Bonzini, QEMU Developers, Richard Henderson
On 16 April 2018 at 17:39, Eduardo Habkost <ehabkost@redhat.com> wrote:
> Last remaining fix for -rc4.
>
> The following changes since commit 042f6a31af3d38eefc6ec995cce1d762c41d4515:
>
> Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2018-04-16' into staging (2018-04-16 15:30:54 +0100)
>
> are available in the Git repository at:
>
> git://github.com/ehabkost/qemu.git tags/x86-next-pull-request
>
> for you to fetch changes up to 0d914f39a77954bf5472b16130aeefe573a068f5:
>
> i386: Don't automatically enable FEAT_KVM_HINTS bits (2018-04-16 13:36:52 -0300)
>
> ----------------------------------------------------------------
> i386: Don't automatically enable FEAT_KVM_HINTS bits
>
> Bug fix for "-cpu host" with newer kernels.
>
> ----------------------------------------------------------------
>
> Eduardo Habkost (1):
> i386: Don't automatically enable FEAT_KVM_HINTS bits
>
Applied, thanks.
-- PMM
^ permalink raw reply [flat|nested] 7+ messages in thread
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2018-04-16 16:39 [Qemu-devel] [PULL 0/1] i386: Don't automatically enable FEAT_KVM_HINTS bits Eduardo Habkost
2018-04-16 16:39 ` [Qemu-devel] [PULL 1/1] " Eduardo Habkost
2018-04-16 16:57 ` [Qemu-devel] [PULL 0/1] " Peter Maydell
2018-04-16 17:42 ` Eduardo Habkost
2018-04-16 17:46 ` Eduardo Habkost
2018-04-16 17:49 ` Peter Maydell
2018-04-17 11:03 ` Peter Maydell
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