| Message ID | 1468416032-7692-11-git-send-email-suravee.suthikulpanit@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Radim, On 7/13/16 21:29, Radim Krčmář wrote: > 2016-07-13 08:20-0500, Suravee Suthikulpanit: >> >From: Suravee Suthikulpanit<Suravee.Suthikulpanit@amd.com> >> > >> >This patch introduces avic_ga_log_notifier, which will be called >> >by IOMMU driver whenever it handles the Guest vAPIC (GA) log entry. >> > >> >Signed-off-by: Suravee Suthikulpanit<suravee.suthikulpanit@amd.com> >> >--- >> > arch/x86/include/asm/kvm_host.h | 2 ++ >> > arch/x86/kvm/svm.c | 68 +++++++++++++++++++++++++++++++++++++++-- >> > 2 files changed, 68 insertions(+), 2 deletions(-) >> > >> >diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >> >index 69e62862..a9466ad 100644 >> >--- a/arch/x86/include/asm/kvm_host.h >> >+++ b/arch/x86/include/asm/kvm_host.h >> >@@ -776,9 +776,11 @@ struct kvm_arch { >> > bool disabled_lapic_found; >> > >> > /* Struct members for AVIC */ >> >+ u32 avic_vm_id; >> > u32 ldr_mode; >> > struct page *avic_logical_id_table_page; >> > struct page *avic_physical_id_table_page; >> >+ struct hlist_node hnode; >> > }; >> > >> > struct kvm_vm_stat { >> >diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c >> >index 16ef31b..1d9f2f6 100644 >> >--- a/arch/x86/kvm/svm.c >> >+++ b/arch/x86/kvm/svm.c >> >@@ -34,6 +34,8 @@ >> > #include <linux/sched.h> >> > #include <linux/trace_events.h> >> > #include <linux/slab.h> >> >+#include <linux/amd-iommu.h> >> >+#include <linux/hashtable.h> >> > >> > #include <asm/apic.h> >> > #include <asm/perf_event.h> >> >@@ -928,6 +930,53 @@ static void svm_disable_lbrv(struct vcpu_svm *svm) >> > set_msr_interception(msrpm, MSR_IA32_LASTINTTOIP, 0, 0); >> > } >> > >> >+/* Note: >> >+ * This hash table is used to map VM_ID to a struct kvm_arch, >> >+ * when handling AMD IOMMU GALOG notification to schedule in >> >+ * a particular vCPU. >> >+ */ >> >+#define SVM_VM_DATA_HASH_BITS 8 >> >+DECLARE_HASHTABLE(svm_vm_data_hash, SVM_VM_DATA_HASH_BITS); >> >+static spinlock_t svm_vm_data_hash_lock; >> >+ >> >+/* Note: >> >+ * This function is called from IOMMU driver to notify >> >+ * SVM to schedule in a particular vCPU of a particular VM. >> >+ */ >> >+static int avic_ga_log_notifier(int vm_id, int vcpu_id) >> >+{ >> >+ unsigned long flags; >> >+ struct kvm_arch *ka = NULL; >> >+ struct kvm_vcpu *vcpu = NULL; >> >+ struct vcpu_svm *svm = NULL; >> >+ >> >+ pr_debug("SVM: %s: vm_id=%#x, vcpu_id=%#x\n", __func__, vm_id, vcpu_id); >> >+ >> >+ spin_lock_irqsave(&svm_vm_data_hash_lock, flags); >> >+ hash_for_each_possible(svm_vm_data_hash, ka, hnode, vm_id) { >> >+ struct kvm *kvm = container_of(ka, struct kvm, arch); >> >+ >> >+ vcpu = kvm_get_vcpu_by_id(kvm, vcpu_id); > The first result is not neccessarily the correct one. > > With more than active 256 VMs, there is a guaranteed collision that > cannot be disambiguated, so VCPUs in both VMs need to be woken up. > > Having a 24 bit vm_id and checking that > kvm->*.avic_id & 0xfffff == vm_id > would help a bit to avoid useless wakeups, but the collision cannot be > avoided. True. What if SVM guarantee that the VM_ID won't conflict b/w any two active VMs? Thanks Suravee. -- 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
2016-07-14 16:43+0700, Suravee Suthikulpanit: > On 7/13/16 21:29, Radim Krčmář wrote: >> 2016-07-13 08:20-0500, Suravee Suthikulpanit: >> > >diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c >> > >+ hash_for_each_possible(svm_vm_data_hash, ka, hnode, vm_id) { >> > >+ struct kvm *kvm = container_of(ka, struct kvm, arch); >> > >+ >> > >+ vcpu = kvm_get_vcpu_by_id(kvm, vcpu_id); >> The first result is not neccessarily the correct one. >> >> With more than active 256 VMs, there is a guaranteed collision that >> cannot be disambiguated, so VCPUs in both VMs need to be woken up. >> >> Having a 24 bit vm_id and checking that >> kvm->*.avic_id & 0xfffff == vm_id >> would help a bit to avoid useless wakeups, but the collision cannot be >> avoided. > > True. What if SVM guarantee that the VM_ID won't conflict b/w any two active > VMs? It is a nice way to avoid the bug you found in amd_iommu_update_ga() and we would send only one wakeup here as well, so it sound like the best solution. -- 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/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 69e62862..a9466ad 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -776,9 +776,11 @@ struct kvm_arch { bool disabled_lapic_found; /* Struct members for AVIC */ + u32 avic_vm_id; u32 ldr_mode; struct page *avic_logical_id_table_page; struct page *avic_physical_id_table_page; + struct hlist_node hnode; }; struct kvm_vm_stat { diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 16ef31b..1d9f2f6 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -34,6 +34,8 @@ #include <linux/sched.h> #include <linux/trace_events.h> #include <linux/slab.h> +#include <linux/amd-iommu.h> +#include <linux/hashtable.h> #include <asm/apic.h> #include <asm/perf_event.h> @@ -928,6 +930,53 @@ static void svm_disable_lbrv(struct vcpu_svm *svm) set_msr_interception(msrpm, MSR_IA32_LASTINTTOIP, 0, 0); } +/* Note: + * This hash table is used to map VM_ID to a struct kvm_arch, + * when handling AMD IOMMU GALOG notification to schedule in + * a particular vCPU. + */ +#define SVM_VM_DATA_HASH_BITS 8 +DECLARE_HASHTABLE(svm_vm_data_hash, SVM_VM_DATA_HASH_BITS); +static spinlock_t svm_vm_data_hash_lock; + +/* Note: + * This function is called from IOMMU driver to notify + * SVM to schedule in a particular vCPU of a particular VM. + */ +static int avic_ga_log_notifier(int vm_id, int vcpu_id) +{ + unsigned long flags; + struct kvm_arch *ka = NULL; + struct kvm_vcpu *vcpu = NULL; + struct vcpu_svm *svm = NULL; + + pr_debug("SVM: %s: vm_id=%#x, vcpu_id=%#x\n", __func__, vm_id, vcpu_id); + + spin_lock_irqsave(&svm_vm_data_hash_lock, flags); + hash_for_each_possible(svm_vm_data_hash, ka, hnode, vm_id) { + struct kvm *kvm = container_of(ka, struct kvm, arch); + + vcpu = kvm_get_vcpu_by_id(kvm, vcpu_id); + break; + } + spin_unlock_irqrestore(&svm_vm_data_hash_lock, flags); + + if (!vcpu) + return 0; + + svm = to_svm(vcpu); + + /* Note: + * At this point, the IOMMU should have already set the pending + * bit in the vAPIC backing page. So, we just need to schedule + * in the vcpu. + */ + if (vcpu->mode == OUTSIDE_GUEST_MODE) + kvm_vcpu_wake_up(vcpu); + + return 0; +} + static __init int svm_hardware_setup(void) { int cpu; @@ -986,10 +1035,15 @@ static __init int svm_hardware_setup(void) if (avic) { if (!npt_enabled || !boot_cpu_has(X86_FEATURE_AVIC) || - !IS_ENABLED(CONFIG_X86_LOCAL_APIC)) + !IS_ENABLED(CONFIG_X86_LOCAL_APIC)) { avic = false; - else + } else { pr_info("AVIC enabled\n"); + + hash_init(svm_vm_data_hash); + spin_lock_init(&svm_vm_data_hash_lock); + amd_iommu_register_ga_log_notifier(&avic_ga_log_notifier); + } } return 0; @@ -1282,16 +1336,22 @@ static int avic_init_backing_page(struct kvm_vcpu *vcpu) static void avic_vm_destroy(struct kvm *kvm) { + unsigned long flags; struct kvm_arch *vm_data = &kvm->arch; if (vm_data->avic_logical_id_table_page) __free_page(vm_data->avic_logical_id_table_page); if (vm_data->avic_physical_id_table_page) __free_page(vm_data->avic_physical_id_table_page); + + spin_lock_irqsave(&svm_vm_data_hash_lock, flags); + hash_del(&vm_data->hnode); + spin_unlock_irqrestore(&svm_vm_data_hash_lock, flags); } static int avic_vm_init(struct kvm *kvm) { + unsigned long flags; int err = -ENOMEM; struct kvm_arch *vm_data = &kvm->arch; struct page *p_page; @@ -1316,6 +1376,10 @@ static int avic_vm_init(struct kvm *kvm) vm_data->avic_logical_id_table_page = l_page; clear_page(page_address(l_page)); + spin_lock_irqsave(&svm_vm_data_hash_lock, flags); + hash_add(svm_vm_data_hash, &vm_data->hnode, vm_data->avic_vm_id); + spin_unlock_irqrestore(&svm_vm_data_hash_lock, flags); + return 0; free_avic: