From bcb902a1ed1ad5e0ceebb9536f392bf6d46219f9 Mon Sep 17 00:00:00 2001 From: Andrew Jones Date: Wed, 10 Mar 2021 14:52:18 +0100 Subject: [PATCH] hw/arm/virt: KVM: The IPA lower bound is 32 The virt machine already checks KVM_CAP_ARM_VM_IPA_SIZE to get the upper bound of the IPA size. If that bound is lower than the highest possible GPA for the machine, then QEMU will error out. However, the IPA is set to 40 when the highest GPA is less than or equal to 40, even when KVM may support an IPA limit as low as 32. This means KVM may fail the VM creation unnecessarily. Additionally, 40 is selected with the value 0, which means use the default, and that gets around a check in some versions of KVM, causing a difficult to debug fail. Always use the IPA size that corresponds to the highest possible GPA, unless it's lower than 32, in which case use 32. Also, we must still use 0 when KVM only supports the legacy fixed 40 bit IPA. Suggested-by: Marc Zyngier Signed-off-by: Andrew Jones Reviewed-by: Eric Auger Reviewed-by: Marc Zyngier Message-id: 20210310135218.255205-3-drjones@redhat.com Signed-off-by: Peter Maydell --- hw/arm/virt.c | 23 ++++++++++++++++------- target/arm/kvm.c | 4 +++- target/arm/kvm_arm.h | 6 ++++-- 3 files changed, 23 insertions(+), 10 deletions(-) diff --git a/hw/arm/virt.c b/hw/arm/virt.c index c08bf11297..aa2bbd14e0 100644 --- a/hw/arm/virt.c +++ b/hw/arm/virt.c @@ -2548,27 +2548,36 @@ static HotplugHandler *virt_machine_get_hotplug_handler(MachineState *machine, static int virt_kvm_type(MachineState *ms, const char *type_str) { VirtMachineState *vms = VIRT_MACHINE(ms); - int max_vm_pa_size = kvm_arm_get_max_vm_ipa_size(ms); - int requested_pa_size; + int max_vm_pa_size, requested_pa_size; + bool fixed_ipa; + + max_vm_pa_size = kvm_arm_get_max_vm_ipa_size(ms, &fixed_ipa); /* we freeze the memory map to compute the highest gpa */ virt_set_memmap(vms); requested_pa_size = 64 - clz64(vms->highest_gpa); + /* + * KVM requires the IPA size to be at least 32 bits. + */ + if (requested_pa_size < 32) { + requested_pa_size = 32; + } + if (requested_pa_size > max_vm_pa_size) { error_report("-m and ,maxmem option values " "require an IPA range (%d bits) larger than " "the one supported by the host (%d bits)", requested_pa_size, max_vm_pa_size); - exit(1); + exit(1); } /* - * By default we return 0 which corresponds to an implicit legacy - * 40b IPA setting. Otherwise we return the actual requested PA - * logsize + * We return the requested PA log size, unless KVM only supports + * the implicit legacy 40b IPA setting, in which case the kvm_type + * must be 0. */ - return requested_pa_size > 40 ? requested_pa_size : 0; + return fixed_ipa ? 0 : requested_pa_size; } static void virt_machine_class_init(ObjectClass *oc, void *data) diff --git a/target/arm/kvm.c b/target/arm/kvm.c index bebea90122..d8381ba224 100644 --- a/target/arm/kvm.c +++ b/target/arm/kvm.c @@ -230,12 +230,14 @@ bool kvm_arm_pmu_supported(void) return kvm_check_extension(kvm_state, KVM_CAP_ARM_PMU_V3); } -int kvm_arm_get_max_vm_ipa_size(MachineState *ms) +int kvm_arm_get_max_vm_ipa_size(MachineState *ms, bool *fixed_ipa) { KVMState *s = KVM_STATE(ms->accelerator); int ret; ret = kvm_check_extension(s, KVM_CAP_ARM_VM_IPA_SIZE); + *fixed_ipa = ret <= 0; + return ret > 0 ? ret : 40; } diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h index 68ec970c4f..34f8daa377 100644 --- a/target/arm/kvm_arm.h +++ b/target/arm/kvm_arm.h @@ -311,10 +311,12 @@ bool kvm_arm_sve_supported(void); /** * kvm_arm_get_max_vm_ipa_size: * @ms: Machine state handle + * @fixed_ipa: True when the IPA limit is fixed at 40. This is the case + * for legacy KVM. * * Returns the number of bits in the IPA address space supported by KVM */ -int kvm_arm_get_max_vm_ipa_size(MachineState *ms); +int kvm_arm_get_max_vm_ipa_size(MachineState *ms, bool *fixed_ipa); /** * kvm_arm_sync_mpstate_to_kvm: @@ -409,7 +411,7 @@ static inline void kvm_arm_add_vcpu_properties(Object *obj) g_assert_not_reached(); } -static inline int kvm_arm_get_max_vm_ipa_size(MachineState *ms) +static inline int kvm_arm_get_max_vm_ipa_size(MachineState *ms, bool *fixed_ipa) { g_assert_not_reached(); }