Re: [Qemu-devel] [PATCH 2/2] target-i386: kvm: enable all supported KVM features for -cpu host
On Fri, 28 Dec 2012 16:37:34 -0200 Eduardo Habkost ehabk...@redhat.com wrote: When using -cpu host, we don't need to use the kvm_default_features variable, as the user is explicitly asking QEMU to enable all feature supported by the host. This changes the kvm_cpu_fill_host() code to use GET_SUPPORTED_CPUID to initialize the kvm_features field, so we get all host KVM features enabled. 1_2 and 1_3 compat machines diff on pv_eoi flag, with this patch 1_2 might have it set. Is it ok from compat machines pov? This will also allow use to properly check/enforce KVM features inside kvm_check_features_against_host() later. For example, we will be able to make this: $ qemu-system-x86_64 -cpu ...,+kvm_pv_eoi,enforce refuse to start if kvm_pv_eoi is not supported by the host (after we fix kvm_check_features_against_host() to check KVM flags as well). It would be nice to have kvm_check_features_against_host() patch in this series to verify that this patch and previous patch works as expected. Signed-off-by: Eduardo Habkost ehabk...@redhat.com --- target-i386/cpu.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/target-i386/cpu.c b/target-i386/cpu.c index 6e2d32d..76f19f0 100644 --- a/target-i386/cpu.c +++ b/target-i386/cpu.c @@ -900,6 +900,8 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def) /* Other KVM-specific feature fields: */ x86_cpu_def-svm_features = kvm_arch_get_supported_cpuid(s, 0x800A, 0, R_EDX); +x86_cpu_def-kvm_features = +kvm_arch_get_supported_cpuid(s, KVM_CPUID_FEATURES, 0, R_EAX); #endif /* CONFIG_KVM */ } -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [Qemu-devel] [PATCH 2/2] target-i386: kvm: enable all supported KVM features for -cpu host
On Wed, Jan 02, 2013 at 03:52:45PM +0100, Igor Mammedov wrote: On Fri, 28 Dec 2012 16:37:34 -0200 Eduardo Habkost ehabk...@redhat.com wrote: When using -cpu host, we don't need to use the kvm_default_features variable, as the user is explicitly asking QEMU to enable all feature supported by the host. This changes the kvm_cpu_fill_host() code to use GET_SUPPORTED_CPUID to initialize the kvm_features field, so we get all host KVM features enabled. 1_2 and 1_3 compat machines diff on pv_eoi flag, with this patch 1_2 might have it set. Is it ok from compat machines pov? -cpu host is completely dependent on host hardware and kernel version, there are no compatibility expectations. This will also allow use to properly check/enforce KVM features inside kvm_check_features_against_host() later. For example, we will be able to make this: $ qemu-system-x86_64 -cpu ...,+kvm_pv_eoi,enforce refuse to start if kvm_pv_eoi is not supported by the host (after we fix kvm_check_features_against_host() to check KVM flags as well). It would be nice to have kvm_check_features_against_host() patch in this series to verify that this patch and previous patch works as expected. The kvm_check_features_against_host() change would be a user-visible behavior change, and I wanted to keep the changes minimal by now. (the main reason I submitted this earlier is to make it easier to clean up the init code for CPU subclasses) I was planning to introduce those behavior changes only after introducing the feature-word array, so the kvm_check_features_against_host() code can become simpler and easier to review (instead of adding 4 additional items to the messy struct model_features_t array). But if you think we can introduce those changes now, I will be happy to send a series that changes that code as well. Signed-off-by: Eduardo Habkost ehabk...@redhat.com --- target-i386/cpu.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/target-i386/cpu.c b/target-i386/cpu.c index 6e2d32d..76f19f0 100644 --- a/target-i386/cpu.c +++ b/target-i386/cpu.c @@ -900,6 +900,8 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def) /* Other KVM-specific feature fields: */ x86_cpu_def-svm_features = kvm_arch_get_supported_cpuid(s, 0x800A, 0, R_EDX); +x86_cpu_def-kvm_features = +kvm_arch_get_supported_cpuid(s, KVM_CPUID_FEATURES, 0, R_EAX); #endif /* CONFIG_KVM */ } -- Eduardo -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [Qemu-devel] [PATCH 2/2] target-i386: kvm: enable all supported KVM features for -cpu host
On Wed, 2 Jan 2013 13:29:10 -0200 Eduardo Habkost ehabk...@redhat.com wrote: On Wed, Jan 02, 2013 at 03:52:45PM +0100, Igor Mammedov wrote: On Fri, 28 Dec 2012 16:37:34 -0200 Eduardo Habkost ehabk...@redhat.com wrote: When using -cpu host, we don't need to use the kvm_default_features variable, as the user is explicitly asking QEMU to enable all feature supported by the host. This changes the kvm_cpu_fill_host() code to use GET_SUPPORTED_CPUID to initialize the kvm_features field, so we get all host KVM features enabled. 1_2 and 1_3 compat machines diff on pv_eoi flag, with this patch 1_2 might have it set. Is it ok from compat machines pov? -cpu host is completely dependent on host hardware and kernel version, there are no compatibility expectations. It's still kind of unpleasant surprise if on the same host qemu-1.3 -cpu host -machine pc-1.2 and qemu-1.3+ -cpu host -machine pc-1.2 would give different pv_eoi feature default, where pv-eoi should be available after -machine pc-1.2 by default. This will also allow use to properly check/enforce KVM features inside kvm_check_features_against_host() later. For example, we will be able to make this: $ qemu-system-x86_64 -cpu ...,+kvm_pv_eoi,enforce refuse to start if kvm_pv_eoi is not supported by the host (after we fix kvm_check_features_against_host() to check KVM flags as well). It would be nice to have kvm_check_features_against_host() patch in this series to verify that this patch and previous patch works as expected. The kvm_check_features_against_host() change would be a user-visible behavior change, and I wanted to keep the changes minimal by now. (the main reason I submitted this earlier is to make it easier to clean up the init code for CPU subclasses) I was planning to introduce those behavior changes only after introducing the feature-word array, so the kvm_check_features_against_host() code can become simpler and easier to review (instead of adding 4 additional items to the messy struct model_features_t array). But if you think we can introduce those changes now, I will be happy to send a series that changes that code as well. It would be better if it and simplifying kvm_check_features_against_host() were in here together. Signed-off-by: Eduardo Habkost ehabk...@redhat.com --- target-i386/cpu.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/target-i386/cpu.c b/target-i386/cpu.c index 6e2d32d..76f19f0 100644 --- a/target-i386/cpu.c +++ b/target-i386/cpu.c @@ -900,6 +900,8 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def) /* Other KVM-specific feature fields: */ x86_cpu_def-svm_features = kvm_arch_get_supported_cpuid(s, 0x800A, 0, R_EDX); +x86_cpu_def-kvm_features = +kvm_arch_get_supported_cpuid(s, KVM_CPUID_FEATURES, 0, R_EAX); #endif /* CONFIG_KVM */ } -- Eduardo -- Regards, Igor -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [Qemu-devel] [PATCH 2/2] target-i386: kvm: enable all supported KVM features for -cpu host
On Wed, Jan 02, 2013 at 09:30:20PM +0100, Igor Mammedov wrote: On Wed, 2 Jan 2013 13:29:10 -0200 Eduardo Habkost ehabk...@redhat.com wrote: On Wed, Jan 02, 2013 at 03:52:45PM +0100, Igor Mammedov wrote: On Fri, 28 Dec 2012 16:37:34 -0200 Eduardo Habkost ehabk...@redhat.com wrote: When using -cpu host, we don't need to use the kvm_default_features variable, as the user is explicitly asking QEMU to enable all feature supported by the host. This changes the kvm_cpu_fill_host() code to use GET_SUPPORTED_CPUID to initialize the kvm_features field, so we get all host KVM features enabled. 1_2 and 1_3 compat machines diff on pv_eoi flag, with this patch 1_2 might have it set. Is it ok from compat machines pov? -cpu host is completely dependent on host hardware and kernel version, there are no compatibility expectations. It's still kind of unpleasant surprise if on the same host qemu-1.3 -cpu host -machine pc-1.2 and qemu-1.3+ -cpu host -machine pc-1.2 would give different pv_eoi feature default, where pv-eoi should be available after -machine pc-1.2 by default. Just like you may end up getting new features enabled by -cpu host after upgrading the kernel, you may end up getting new features enabled by -cpu host after upgrading qemu. If you don't like surprises, don't use -cpu host. ;-) I don't think machine-types exist to avoid user surprise, they exist to keep compatibility (which is not expected to happen when using -cpu host). Keeping compatibility is hard enough in the cases where we really need it, I don't think it is worth the extra work and complexity for an use case where compatibility is not expected. This will also allow use to properly check/enforce KVM features inside kvm_check_features_against_host() later. For example, we will be able to make this: $ qemu-system-x86_64 -cpu ...,+kvm_pv_eoi,enforce refuse to start if kvm_pv_eoi is not supported by the host (after we fix kvm_check_features_against_host() to check KVM flags as well). It would be nice to have kvm_check_features_against_host() patch in this series to verify that this patch and previous patch works as expected. The kvm_check_features_against_host() change would be a user-visible behavior change, and I wanted to keep the changes minimal by now. (the main reason I submitted this earlier is to make it easier to clean up the init code for CPU subclasses) I was planning to introduce those behavior changes only after introducing the feature-word array, so the kvm_check_features_against_host() code can become simpler and easier to review (instead of adding 4 additional items to the messy struct model_features_t array). But if you think we can introduce those changes now, I will be happy to send a series that changes that code as well. It would be better if it and simplifying kvm_check_features_against_host() were in here together. The best way I see to simplify kvm_check_features_against_host() requires the feature words array patch, that touches _lots_ of code. I wanted to avoid adding such an intrusive patch as a dependency. Signed-off-by: Eduardo Habkost ehabk...@redhat.com --- target-i386/cpu.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/target-i386/cpu.c b/target-i386/cpu.c index 6e2d32d..76f19f0 100644 --- a/target-i386/cpu.c +++ b/target-i386/cpu.c @@ -900,6 +900,8 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def) /* Other KVM-specific feature fields: */ x86_cpu_def-svm_features = kvm_arch_get_supported_cpuid(s, 0x800A, 0, R_EDX); +x86_cpu_def-kvm_features = +kvm_arch_get_supported_cpuid(s, KVM_CPUID_FEATURES, 0, R_EAX); #endif /* CONFIG_KVM */ } -- Eduardo -- Regards, Igor -- Eduardo -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
