| Message ID | 1356719854-16401-2-git-send-email-ehabkost@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Fri, 28 Dec 2012 16:37:33 -0200 Eduardo Habkost <ehabkost@redhat.com> wrote: > The existing -cpu host code simply set every bit inside svm_features > (initializing it to -1), and that makes it impossible to make the > enforce/check options work properly when the user asks for SVM features > explicitly in the command-line. > > So, instead of initializing svm_features to -1, use GET_SUPPORTED_CPUID > to fill only the bits that are supported by the host (just like we do > for all other CPUID feature words inside kvm_cpu_fill_host()). > > This will keep the existing behavior (as filter_features_for_kvm() > already uses GET_SUPPORTED_CPUID to filter svm_features), but will allow > us to properly check for KVM features inside > kvm_check_features_against_host() later. > > For example, we will be able to make this: > > $ qemu-system-x86_64 -cpu ...,+pfthreshold,enforce > > refuse to start if the SVM "pfthreshold" feature is not supported by the > host (after we fix kvm_check_features_against_host() to check SVM flags > as well). > > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> Reviewed-By: Igor Mammedov <imammedo@redhat.com> > --- > target-i386/cpu.c | 11 ++++------- > 1 file changed, 4 insertions(+), 7 deletions(-) > > diff --git a/target-i386/cpu.c b/target-i386/cpu.c > index 3cd1cee..6e2d32d 100644 > --- a/target-i386/cpu.c > +++ b/target-i386/cpu.c > @@ -897,13 +897,10 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def) > } > } > > - /* > - * Every SVM feature requires emulation support in KVM - so we can't > just > - * read the host features here. KVM might even support SVM features not > - * available on the host hardware. Just set all bits and mask out the > - * unsupported ones later. > - */ > - x86_cpu_def->svm_features = -1; > + /* Other KVM-specific feature fields: */ > + x86_cpu_def->svm_features = > + kvm_arch_get_supported_cpuid(s, 0x8000000A, 0, R_EDX); > + > #endif /* CONFIG_KVM */ > } >
Am 28.12.2012 19:37, schrieb Eduardo Habkost: > The existing -cpu host code simply set every bit inside svm_features > (initializing it to -1), and that makes it impossible to make the > enforce/check options work properly when the user asks for SVM features > explicitly in the command-line. > > So, instead of initializing svm_features to -1, use GET_SUPPORTED_CPUID > to fill only the bits that are supported by the host (just like we do > for all other CPUID feature words inside kvm_cpu_fill_host()). > > This will keep the existing behavior (as filter_features_for_kvm() > already uses GET_SUPPORTED_CPUID to filter svm_features), but will allow > us to properly check for KVM features inside > kvm_check_features_against_host() later. > > For example, we will be able to make this: > > $ qemu-system-x86_64 -cpu ...,+pfthreshold,enforce > > refuse to start if the SVM "pfthreshold" feature is not supported by the > host (after we fix kvm_check_features_against_host() to check SVM flags > as well). > > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> > --- > target-i386/cpu.c | 11 ++++------- > 1 file changed, 4 insertions(+), 7 deletions(-) > > diff --git a/target-i386/cpu.c b/target-i386/cpu.c > index 3cd1cee..6e2d32d 100644 > --- a/target-i386/cpu.c > +++ b/target-i386/cpu.c > @@ -897,13 +897,10 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def) > } > } > > - /* > - * Every SVM feature requires emulation support in KVM - so we can't just > - * read the host features here. KVM might even support SVM features not > - * available on the host hardware. Just set all bits and mask out the > - * unsupported ones later. > - */ > - x86_cpu_def->svm_features = -1; > + /* Other KVM-specific feature fields: */ > + x86_cpu_def->svm_features = > + kvm_arch_get_supported_cpuid(s, 0x8000000A, 0, R_EDX); Is there no #define for this, similar to KVM_CPUID_FEATURES in 2/2? FWIW indentation looks odd. Andreas > + > #endif /* CONFIG_KVM */ > } > >
On Wed, Jan 02, 2013 at 03:39:03PM +0100, Andreas Färber wrote: > Am 28.12.2012 19:37, schrieb Eduardo Habkost: > > The existing -cpu host code simply set every bit inside svm_features > > (initializing it to -1), and that makes it impossible to make the > > enforce/check options work properly when the user asks for SVM features > > explicitly in the command-line. > > > > So, instead of initializing svm_features to -1, use GET_SUPPORTED_CPUID > > to fill only the bits that are supported by the host (just like we do > > for all other CPUID feature words inside kvm_cpu_fill_host()). > > > > This will keep the existing behavior (as filter_features_for_kvm() > > already uses GET_SUPPORTED_CPUID to filter svm_features), but will allow > > us to properly check for KVM features inside > > kvm_check_features_against_host() later. > > > > For example, we will be able to make this: > > > > $ qemu-system-x86_64 -cpu ...,+pfthreshold,enforce > > > > refuse to start if the SVM "pfthreshold" feature is not supported by the > > host (after we fix kvm_check_features_against_host() to check SVM flags > > as well). > > > > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> > > --- > > target-i386/cpu.c | 11 ++++------- > > 1 file changed, 4 insertions(+), 7 deletions(-) > > > > diff --git a/target-i386/cpu.c b/target-i386/cpu.c > > index 3cd1cee..6e2d32d 100644 > > --- a/target-i386/cpu.c > > +++ b/target-i386/cpu.c > > @@ -897,13 +897,10 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def) > > } > > } > > > > - /* > > - * Every SVM feature requires emulation support in KVM - so we can't just > > - * read the host features here. KVM might even support SVM features not > > - * available on the host hardware. Just set all bits and mask out the > > - * unsupported ones later. > > - */ > > - x86_cpu_def->svm_features = -1; > > + /* Other KVM-specific feature fields: */ > > + x86_cpu_def->svm_features = > > + kvm_arch_get_supported_cpuid(s, 0x8000000A, 0, R_EDX); > > Is there no #define for this, similar to KVM_CPUID_FEATURES in 2/2? I believve KVM_CPUID_FEATURES is the exception, all other leaves have their own numbers hardcoded in the code. (The way I plan to fix this is to introduce the feature-array and a CPUID leaf/register table for the feature-array, so kvm_cpu_fill_host(), filter_features_for_kvm(), kvm_check_features_against_host() & similar functions would always handle exactly the same set of CPUID leaves, by simply looking at the table). > FWIW indentation looks odd. Oops, I intended to follow the existing style used for ext2_features and ext3_features and use 8 spaces instead of 12. I will resubmit.
diff --git a/target-i386/cpu.c b/target-i386/cpu.c index 3cd1cee..6e2d32d 100644 --- a/target-i386/cpu.c +++ b/target-i386/cpu.c @@ -897,13 +897,10 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def) } } - /* - * Every SVM feature requires emulation support in KVM - so we can't just - * read the host features here. KVM might even support SVM features not - * available on the host hardware. Just set all bits and mask out the - * unsupported ones later. - */ - x86_cpu_def->svm_features = -1; + /* Other KVM-specific feature fields: */ + x86_cpu_def->svm_features = + kvm_arch_get_supported_cpuid(s, 0x8000000A, 0, R_EDX); + #endif /* CONFIG_KVM */ }
The existing -cpu host code simply set every bit inside svm_features (initializing it to -1), and that makes it impossible to make the enforce/check options work properly when the user asks for SVM features explicitly in the command-line. So, instead of initializing svm_features to -1, use GET_SUPPORTED_CPUID to fill only the bits that are supported by the host (just like we do for all other CPUID feature words inside kvm_cpu_fill_host()). This will keep the existing behavior (as filter_features_for_kvm() already uses GET_SUPPORTED_CPUID to filter svm_features), but will allow us to properly check for KVM features inside kvm_check_features_against_host() later. For example, we will be able to make this: $ qemu-system-x86_64 -cpu ...,+pfthreshold,enforce refuse to start if the SVM "pfthreshold" feature is not supported by the host (after we fix kvm_check_features_against_host() to check SVM flags as well). Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> --- target-i386/cpu.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-)