From b130a8f70cbbf907c399799bd1073a78763ca0e7 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 28 May 2020 14:12:58 +0100 Subject: [PATCH] KVM: arm64: Check advertised Stage-2 page size capability With ARMv8.5-GTG, the hardware (or more likely a hypervisor) can advertise the supported Stage-2 page sizes. Let's check this at boot time. Reviewed-by: Suzuki K Poulose Reviewed-by: Alexandru Elisei Signed-off-by: Marc Zyngier Signed-off-by: Will Deacon --- arch/arm64/include/asm/kvm_host.h | 2 +- arch/arm64/include/asm/sysreg.h | 3 +++ arch/arm64/kernel/cpufeature.c | 18 ++++++++++++++++++ arch/arm64/kvm/reset.c | 37 +++++++++++++++++++++++++++++++++++-- virt/kvm/arm/arm.c | 4 +--- 5 files changed, 58 insertions(+), 6 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 32c8a67..7dd8fef 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -670,7 +670,7 @@ static inline int kvm_arm_have_ssbd(void) void kvm_vcpu_load_sysregs(struct kvm_vcpu *vcpu); void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu); -void kvm_set_ipa_limit(void); +int kvm_set_ipa_limit(void); #define __KVM_HAVE_ARCH_VM_ALLOC struct kvm *kvm_arch_alloc_vm(void); diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index fa9d02c..efe368e 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -703,6 +703,9 @@ #define ID_AA64ZFR0_SVEVER_SVE2 0x1 /* id_aa64mmfr0 */ +#define ID_AA64MMFR0_TGRAN4_2_SHIFT 40 +#define ID_AA64MMFR0_TGRAN64_2_SHIFT 36 +#define ID_AA64MMFR0_TGRAN16_2_SHIFT 32 #define ID_AA64MMFR0_TGRAN4_SHIFT 28 #define ID_AA64MMFR0_TGRAN64_SHIFT 24 #define ID_AA64MMFR0_TGRAN16_SHIFT 20 diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 7437b8c..b3202a9 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -268,6 +268,24 @@ static const struct arm64_ftr_bits ftr_id_aa64zfr0[] = { static const struct arm64_ftr_bits ftr_id_aa64mmfr0[] = { /* + * Page size not being supported at Stage-2 is not fatal. You + * just give up KVM if PAGE_SIZE isn't supported there. Go fix + * your favourite nesting hypervisor. + * + * There is a small corner case where the hypervisor explicitly + * advertises a given granule size at Stage-2 (value 2) on some + * vCPUs, and uses the fallback to Stage-1 (value 0) for other + * vCPUs. Although this is not forbidden by the architecture, it + * indicates that the hypervisor is being silly (or buggy). + * + * We make no effort to cope with this and pretend that if these + * fields are inconsistent across vCPUs, then it isn't worth + * trying to bring KVM up. + */ + ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_EXACT, ID_AA64MMFR0_TGRAN4_2_SHIFT, 4, 1), + ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_EXACT, ID_AA64MMFR0_TGRAN64_2_SHIFT, 4, 1), + ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_EXACT, ID_AA64MMFR0_TGRAN16_2_SHIFT, 4, 1), + /* * We already refuse to boot CPUs that don't support our configured * page size, so we can only detect mismatches for a page size other * than the one we're currently using. Unfortunately, SoCs like this diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c index d8800ef..70cd7bc 100644 --- a/arch/arm64/kvm/reset.c +++ b/arch/arm64/kvm/reset.c @@ -337,14 +337,45 @@ u32 get_kvm_ipa_limit(void) return kvm_ipa_limit; } -void kvm_set_ipa_limit(void) +int kvm_set_ipa_limit(void) { - unsigned int ipa_max, pa_max, va_max, parange; + unsigned int ipa_max, pa_max, va_max, parange, tgran_2; u64 mmfr0; mmfr0 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1); parange = cpuid_feature_extract_unsigned_field(mmfr0, ID_AA64MMFR0_PARANGE_SHIFT); + + /* + * Check with ARMv8.5-GTG that our PAGE_SIZE is supported at + * Stage-2. If not, things will stop very quickly. + */ + switch (PAGE_SIZE) { + default: + case SZ_4K: + tgran_2 = ID_AA64MMFR0_TGRAN4_2_SHIFT; + break; + case SZ_16K: + tgran_2 = ID_AA64MMFR0_TGRAN16_2_SHIFT; + break; + case SZ_64K: + tgran_2 = ID_AA64MMFR0_TGRAN64_2_SHIFT; + break; + } + + switch (cpuid_feature_extract_unsigned_field(mmfr0, tgran_2)) { + default: + case 1: + kvm_err("PAGE_SIZE not supported at Stage-2, giving up\n"); + return -EINVAL; + case 0: + kvm_debug("PAGE_SIZE supported at Stage-2 (default)\n"); + break; + case 2: + kvm_debug("PAGE_SIZE supported at Stage-2 (advertised)\n"); + break; + } + pa_max = id_aa64mmfr0_parange_to_phys_shift(parange); /* Clamp the IPA limit to the PA size supported by the kernel */ @@ -378,6 +409,8 @@ void kvm_set_ipa_limit(void) "KVM IPA limit (%d bit) is smaller than default size\n", ipa_max); kvm_ipa_limit = ipa_max; kvm_info("IPA Size Limit: %dbits\n", kvm_ipa_limit); + + return 0; } /* diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index 48d0ec4..53b3ba9 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -1387,9 +1387,7 @@ static inline void hyp_cpu_pm_exit(void) static int init_common_resources(void) { - kvm_set_ipa_limit(); - - return 0; + return kvm_set_ipa_limit(); } static int init_subsystems(void) -- 2.7.4