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Fri, 10 Sep 2021 11:04:09 -0700 (PDT) MIME-Version: 1.0 References: <20210909013818.1191270-1-rananta@google.com> <20210909013818.1191270-10-rananta@google.com> <20210909075643.fhngqu6tqrpe33gl@gator> <20210910081001.4gljsvmcovvoylwt@gator> In-Reply-To: <20210910081001.4gljsvmcovvoylwt@gator> From: Raghavendra Rao Ananta Date: Fri, 10 Sep 2021 11:03:58 -0700 Message-ID: Subject: Re: [PATCH v4 09/18] KVM: arm64: selftests: Add guest support to get the vcpuid To: Andrew Jones Cc: kvm@vger.kernel.org, Will Deacon , Catalin Marinas , Peter Shier , linux-kernel@vger.kernel.org, Marc Zyngier , Paolo Bonzini , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Fri, Sep 10, 2021 at 1:10 AM Andrew Jones wrote: > > On Thu, Sep 09, 2021 at 10:10:56AM -0700, Raghavendra Rao Ananta wrote: > > On Thu, Sep 9, 2021 at 12:56 AM Andrew Jones wrote: > > > > > > On Thu, Sep 09, 2021 at 01:38:09AM +0000, Raghavendra Rao Ananta wrote: > ... > > > > + for (i = 0; i < KVM_MAX_VCPUS; i++) { > > > > + vcpuid = vcpuid_map[i].vcpuid; > > > > + GUEST_ASSERT_1(vcpuid != VM_VCPUID_MAP_INVAL, mpidr); > > > > > > We don't want this assert if it's possible to have sparse maps, which > > > it probably isn't ever going to be, but... > > > > > If you look at the way the array is arranged, the element with > > VM_VCPUID_MAP_INVAL acts as a sentinel for us and all the proper > > elements would lie before this. So, I don't think we'd have a sparse > > array here. > > If we switch to my suggestion of adding map entries at vcpu-add time and > removing them at vcpu-rm time, then the array may become sparse depending > on the order of removals. > Oh, I get it now. But like you mentioned, we add entries to the map while the vCPUs are getting added and then sync_global_to_guest() later. This seems like a lot of maintainance, unless I'm interpreting it wrong or not seeing an advantage. I like your idea of coming up an arch-independent interface, however. So I modified it similar to the familiar ucall interface that we have and does everything in one shot to avoid any confusion: diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h index 010b59b13917..0e87cb0c980b 100644 --- a/tools/testing/selftests/kvm/include/kvm_util.h +++ b/tools/testing/selftests/kvm/include/kvm_util.h @@ -400,4 +400,24 @@ uint64_t get_ucall(struct kvm_vm *vm, uint32_t vcpu_id, struct ucall *uc); int vm_get_stats_fd(struct kvm_vm *vm); int vcpu_get_stats_fd(struct kvm_vm *vm, uint32_t vcpuid); +#define VM_CPUID_MAP_INVAL -1 + +struct vm_cpuid_map { + uint64_t hw_cpuid; + int vcpuid; +}; + +/* + * Create a vcpuid:hw_cpuid map and export it to the guest + * + * Input Args: + * vm - KVM VM. + * + * Output Args: None + * + * Must be called after all the vCPUs are added to the VM + */ +void vm_cpuid_map_init(struct kvm_vm *vm); +int guest_get_vcpuid(void); + #endif /* SELFTEST_KVM_UTIL_H */ diff --git a/tools/testing/selftests/kvm/lib/aarch64/processor.c b/tools/testing/selftests/kvm/lib/aarch64/processor.c index db64ee206064..e796bb3984a6 100644 --- a/tools/testing/selftests/kvm/lib/aarch64/processor.c +++ b/tools/testing/selftests/kvm/lib/aarch64/processor.c @@ -16,6 +16,8 @@ static vm_vaddr_t exception_handlers; +static struct vm_cpuid_map cpuid_map[KVM_MAX_VCPUS]; + static uint64_t page_align(struct kvm_vm *vm, uint64_t v) { return (v + vm->page_size) & ~(vm->page_size - 1); @@ -426,3 +428,42 @@ void vm_install_exception_handler(struct kvm_vm *vm, int vector, assert(vector < VECTOR_NUM); handlers->exception_handlers[vector][0] = handler; } + +void vm_cpuid_map_init(struct kvm_vm *vm) +{ + int i = 0; + struct vcpu *vcpu; + struct vm_cpuid_map *map; + + TEST_ASSERT(!list_empty(&vm->vcpus), "vCPUs must have been created\n"); + + list_for_each_entry(vcpu, &vm->vcpus, list) { + map = &cpuid_map[i++]; + map->vcpuid = vcpu->id; + get_reg(vm, vcpu->id, KVM_ARM64_SYS_REG(SYS_MPIDR_EL1), &map->hw_cpuid); + map->hw_cpuid &= MPIDR_HWID_BITMASK; + } + + if (i < KVM_MAX_VCPUS) + cpuid_map[i].vcpuid = VM_CPUID_MAP_INVAL; + + sync_global_to_guest(vm, cpuid_map); +} + +int guest_get_vcpuid(void) +{ + int i, vcpuid; + uint64_t mpidr = read_sysreg(mpidr_el1) & MPIDR_HWID_BITMASK; + + for (i = 0; i < KVM_MAX_VCPUS; i++) { + vcpuid = cpuid_map[i].vcpuid; + + /* Was this vCPU added to the VM after the map was initialized? */ + GUEST_ASSERT_1(vcpuid != VM_CPUID_MAP_INVAL, mpidr); + + if (mpidr == cpuid_map[i].hw_cpuid) + return vcpuid; + } + + /* We should not be reaching here */ + GUEST_ASSERT_1(0, mpidr); + return -1; +} This would ensure that we don't have a sparse array and can use the last non-vCPU element as a sentinal node. If you still feel preparing the map as and when the vCPUs are created makes more sense, I can go for it. Regards, Raghavendra > Thanks, > drew > _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm