| Message ID | 1379861095-628-7-git-send-email-bp@alien8.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
(CCing qemu-devel and libvir-list) On Sun, Sep 22, 2013 at 04:44:55PM +0200, Borislav Petkov wrote: > From: Borislav Petkov <bp@suse.de> > > Add support for the KVM_GET_EMULATED_CPUID ioctl and leave feature bits > enabled, when requested by userspace, if kvm emulates them. > > Signed-off-by: Borislav Petkov <bp@suse.de> This will break some assumptions about the semantics of "-cpu host", that today means "enable every single feature that can be enabled in the host". This, in turn, breaks the assumption that "-cpu host" can be used by libvirt to get information about all CPU features supported by the host. So, I have two questions: 1) Should "-cpu host" enable GET_EMULATED_CPUID features? (I believe the answer is "no"); 2) If not, we need a new mechanism to let libvirt know which features can be enabled on a host (in a way that would allow libvirt to easily calculate the set of possible destination hosts to which a VM can be migrated, before deciding to migrate it). This interface is getting complex enough for me to consider simply asking libvirt developers to call GET_EMULATED_CPUID and GET_SUPPORTED_CPUID directly, instead of asking QEMU for information. But if libvirt does that, it needs a way to know if it's running a QEMU version that supports GET_EMULATED_CPUID, or an old version that supports only GET_SUPPORTED_CPUID. Another alternative is to simply let libvirt ignore GET_EMULATED_CPUID by now, and treat GET_EMULATED_CPUID features as not supported by the host. But then it will break the use cases that prompted the creation of GET_EMULATED_CPUID in the first place. > --- > include/sysemu/kvm.h | 4 ++++ > linux-headers/linux/kvm.h | 4 ++++ > target-i386/cpu.c | 7 +++++++ > target-i386/kvm.c | 38 ++++++++++++++++++++++++++++++++++---- > 4 files changed, 49 insertions(+), 4 deletions(-) > > diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h > index 9bbe3db1464e..8eda1ada848a 100644 > --- a/include/sysemu/kvm.h > +++ b/include/sysemu/kvm.h > @@ -265,6 +265,10 @@ int kvm_check_extension(KVMState *s, unsigned int extension); > > uint32_t kvm_arch_get_supported_cpuid(KVMState *env, uint32_t function, > uint32_t index, int reg); > + > +uint32_t kvm_arch_get_emulated_cpuid(KVMState *env, uint32_t function, > + uint32_t index, int reg); > + > void kvm_cpu_synchronize_state(CPUState *cpu); > > /* generic hooks - to be moved/refactored once there are more users */ > diff --git a/linux-headers/linux/kvm.h b/linux-headers/linux/kvm.h > index c614070662e1..edc8f2db1f8d 100644 > --- a/linux-headers/linux/kvm.h > +++ b/linux-headers/linux/kvm.h > @@ -541,6 +541,7 @@ struct kvm_ppc_smmu_info { > #define KVM_TRACE_ENABLE __KVM_DEPRECATED_MAIN_W_0x06 > #define KVM_TRACE_PAUSE __KVM_DEPRECATED_MAIN_0x07 > #define KVM_TRACE_DISABLE __KVM_DEPRECATED_MAIN_0x08 > +#define KVM_GET_EMULATED_CPUID _IOWR(KVMIO, 0x09, struct kvm_cpuid2) > > /* > * Extension capability list. > @@ -666,6 +667,9 @@ struct kvm_ppc_smmu_info { > #define KVM_CAP_IRQ_MPIC 90 > #define KVM_CAP_PPC_RTAS 91 > #define KVM_CAP_IRQ_XICS 92 > +#define KVM_CAP_ARM_EL1_32BIT 93 > +#define KVM_CAP_SPAPR_MULTITCE 94 > +#define KVM_CAP_EXT_EMUL_CPUID 95 > > #ifdef KVM_CAP_IRQ_ROUTING > > diff --git a/target-i386/cpu.c b/target-i386/cpu.c > index c36345e426d7..5406348ceb4a 100644 > --- a/target-i386/cpu.c > +++ b/target-i386/cpu.c > @@ -1850,7 +1850,14 @@ static void filter_features_for_kvm(X86CPU *cpu) > wi->cpuid_ecx, > wi->cpuid_reg); > uint32_t requested_features = env->features[w]; > + > + uint32_t emul_features = kvm_arch_get_emulated_cpuid(s, wi->cpuid_eax, > + wi->cpuid_ecx, > + wi->cpuid_reg); > + > env->features[w] &= host_feat; > + env->features[w] |= (requested_features & emul_features); > + I find the above logic confusing: you remove a few bits just to re-add them later. Isn't easier and simpler to simply do: env->features[w] &= (host_feat | emul_features); ? > cpu->filtered_features[w] = requested_features & ~env->features[w]; > } > } > diff --git a/target-i386/kvm.c b/target-i386/kvm.c > index 749aa09a21a6..7f598f01bda5 100644 > --- a/target-i386/kvm.c > +++ b/target-i386/kvm.c > @@ -80,7 +80,7 @@ bool kvm_allows_irq0_override(void) > return !kvm_irqchip_in_kernel() || kvm_has_gsi_routing(); > } > > -static struct kvm_cpuid2 *try_get_cpuid(KVMState *s, int max) > +static struct kvm_cpuid2 *try_get_cpuid(KVMState *s, int ioctl, int max) > { > struct kvm_cpuid2 *cpuid; > int r, size; > @@ -88,7 +88,7 @@ static struct kvm_cpuid2 *try_get_cpuid(KVMState *s, int max) > size = sizeof(*cpuid) + max * sizeof(*cpuid->entries); > cpuid = (struct kvm_cpuid2 *)g_malloc0(size); > cpuid->nent = max; > - r = kvm_ioctl(s, KVM_GET_SUPPORTED_CPUID, cpuid); > + r = kvm_ioctl(s, ioctl, cpuid); > if (r == 0 && cpuid->nent >= max) { > r = -E2BIG; > } > @@ -97,7 +97,10 @@ static struct kvm_cpuid2 *try_get_cpuid(KVMState *s, int max) > g_free(cpuid); > return NULL; > } else { > - fprintf(stderr, "KVM_GET_SUPPORTED_CPUID failed: %s\n", > + fprintf(stderr, "%s failed: %s\n", > + (ioctl == (int)KVM_GET_SUPPORTED_CPUID > + ? "KVM_GET_SUPPORTED_CPUID" > + : "KVM_GET_EMULATED_CPUID"), > strerror(-r)); > exit(1); > } > @@ -112,7 +115,17 @@ static struct kvm_cpuid2 *get_supported_cpuid(KVMState *s) > { > struct kvm_cpuid2 *cpuid; > int max = 1; > - while ((cpuid = try_get_cpuid(s, max)) == NULL) { > + while ((cpuid = try_get_cpuid(s, KVM_GET_SUPPORTED_CPUID, max)) == NULL) { > + max *= 2; > + } > + return cpuid; > +} > + > +static struct kvm_cpuid2 *get_emulated_cpuid(KVMState *s) > +{ > + struct kvm_cpuid2 *cpuid; > + int max = 1; > + while ((cpuid = try_get_cpuid(s, KVM_GET_EMULATED_CPUID, max)) == NULL) { > max *= 2; > } > return cpuid; > @@ -241,6 +254,23 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function, > return ret; > } > > +uint32_t kvm_arch_get_emulated_cpuid(KVMState *s, uint32_t function, > + uint32_t index, int reg) > +{ > + struct kvm_cpuid2 *cpuid __attribute__((unused)); > + > + if (!kvm_check_extension(s, KVM_CAP_EXT_EMUL_CPUID)) > + return 0; > + > + cpuid = get_emulated_cpuid(s); > + > + struct kvm_cpuid_entry2 *entry = cpuid_find_entry(cpuid, function, index); > + if (entry) > + return cpuid_entry_get_reg(entry, reg); > + > + return 0; > +} > + > typedef struct HWPoisonPage { > ram_addr_t ram_addr; > QLIST_ENTRY(HWPoisonPage) list; > -- > 1.8.4 > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h index 9bbe3db1464e..8eda1ada848a 100644 --- a/include/sysemu/kvm.h +++ b/include/sysemu/kvm.h @@ -265,6 +265,10 @@ int kvm_check_extension(KVMState *s, unsigned int extension); uint32_t kvm_arch_get_supported_cpuid(KVMState *env, uint32_t function, uint32_t index, int reg); + +uint32_t kvm_arch_get_emulated_cpuid(KVMState *env, uint32_t function, + uint32_t index, int reg); + void kvm_cpu_synchronize_state(CPUState *cpu); /* generic hooks - to be moved/refactored once there are more users */ diff --git a/linux-headers/linux/kvm.h b/linux-headers/linux/kvm.h index c614070662e1..edc8f2db1f8d 100644 --- a/linux-headers/linux/kvm.h +++ b/linux-headers/linux/kvm.h @@ -541,6 +541,7 @@ struct kvm_ppc_smmu_info { #define KVM_TRACE_ENABLE __KVM_DEPRECATED_MAIN_W_0x06 #define KVM_TRACE_PAUSE __KVM_DEPRECATED_MAIN_0x07 #define KVM_TRACE_DISABLE __KVM_DEPRECATED_MAIN_0x08 +#define KVM_GET_EMULATED_CPUID _IOWR(KVMIO, 0x09, struct kvm_cpuid2) /* * Extension capability list. @@ -666,6 +667,9 @@ struct kvm_ppc_smmu_info { #define KVM_CAP_IRQ_MPIC 90 #define KVM_CAP_PPC_RTAS 91 #define KVM_CAP_IRQ_XICS 92 +#define KVM_CAP_ARM_EL1_32BIT 93 +#define KVM_CAP_SPAPR_MULTITCE 94 +#define KVM_CAP_EXT_EMUL_CPUID 95 #ifdef KVM_CAP_IRQ_ROUTING diff --git a/target-i386/cpu.c b/target-i386/cpu.c index c36345e426d7..5406348ceb4a 100644 --- a/target-i386/cpu.c +++ b/target-i386/cpu.c @@ -1850,7 +1850,14 @@ static void filter_features_for_kvm(X86CPU *cpu) wi->cpuid_ecx, wi->cpuid_reg); uint32_t requested_features = env->features[w]; + + uint32_t emul_features = kvm_arch_get_emulated_cpuid(s, wi->cpuid_eax, + wi->cpuid_ecx, + wi->cpuid_reg); + env->features[w] &= host_feat; + env->features[w] |= (requested_features & emul_features); + cpu->filtered_features[w] = requested_features & ~env->features[w]; } } diff --git a/target-i386/kvm.c b/target-i386/kvm.c index 749aa09a21a6..7f598f01bda5 100644 --- a/target-i386/kvm.c +++ b/target-i386/kvm.c @@ -80,7 +80,7 @@ bool kvm_allows_irq0_override(void) return !kvm_irqchip_in_kernel() || kvm_has_gsi_routing(); } -static struct kvm_cpuid2 *try_get_cpuid(KVMState *s, int max) +static struct kvm_cpuid2 *try_get_cpuid(KVMState *s, int ioctl, int max) { struct kvm_cpuid2 *cpuid; int r, size; @@ -88,7 +88,7 @@ static struct kvm_cpuid2 *try_get_cpuid(KVMState *s, int max) size = sizeof(*cpuid) + max * sizeof(*cpuid->entries); cpuid = (struct kvm_cpuid2 *)g_malloc0(size); cpuid->nent = max; - r = kvm_ioctl(s, KVM_GET_SUPPORTED_CPUID, cpuid); + r = kvm_ioctl(s, ioctl, cpuid); if (r == 0 && cpuid->nent >= max) { r = -E2BIG; } @@ -97,7 +97,10 @@ static struct kvm_cpuid2 *try_get_cpuid(KVMState *s, int max) g_free(cpuid); return NULL; } else { - fprintf(stderr, "KVM_GET_SUPPORTED_CPUID failed: %s\n", + fprintf(stderr, "%s failed: %s\n", + (ioctl == (int)KVM_GET_SUPPORTED_CPUID + ? "KVM_GET_SUPPORTED_CPUID" + : "KVM_GET_EMULATED_CPUID"), strerror(-r)); exit(1); } @@ -112,7 +115,17 @@ static struct kvm_cpuid2 *get_supported_cpuid(KVMState *s) { struct kvm_cpuid2 *cpuid; int max = 1; - while ((cpuid = try_get_cpuid(s, max)) == NULL) { + while ((cpuid = try_get_cpuid(s, KVM_GET_SUPPORTED_CPUID, max)) == NULL) { + max *= 2; + } + return cpuid; +} + +static struct kvm_cpuid2 *get_emulated_cpuid(KVMState *s) +{ + struct kvm_cpuid2 *cpuid; + int max = 1; + while ((cpuid = try_get_cpuid(s, KVM_GET_EMULATED_CPUID, max)) == NULL) { max *= 2; } return cpuid; @@ -241,6 +254,23 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function, return ret; } +uint32_t kvm_arch_get_emulated_cpuid(KVMState *s, uint32_t function, + uint32_t index, int reg) +{ + struct kvm_cpuid2 *cpuid __attribute__((unused)); + + if (!kvm_check_extension(s, KVM_CAP_EXT_EMUL_CPUID)) + return 0; + + cpuid = get_emulated_cpuid(s); + + struct kvm_cpuid_entry2 *entry = cpuid_find_entry(cpuid, function, index); + if (entry) + return cpuid_entry_get_reg(entry, reg); + + return 0; +} + typedef struct HWPoisonPage { ram_addr_t ram_addr; QLIST_ENTRY(HWPoisonPage) list;