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Wed, 22 Apr 2020 06:35:27 -0700 (PDT) Received: from [10.37.12.172] (unknown [10.37.12.172]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 86A923F6CF; Wed, 22 Apr 2020 06:35:23 -0700 (PDT) Subject: Re: [PATCH 01/26] KVM: arm64: Check advertised Stage-2 page size capability To: maz@kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org References: <20200422120050.3693593-1-maz@kernel.org> <20200422120050.3693593-2-maz@kernel.org> From: Suzuki K Poulose Message-ID: <32cc9a60-1b47-f3f7-d18d-d39db397ea55@arm.com> Date: Wed, 22 Apr 2020 14:40:10 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20200422120050.3693593-2-maz@kernel.org> Content-Language: en-US Cc: will@kernel.org, andre.przywara@arm.com, dave.martin@arm.com, gcherian@marvell.com, prime.zeng@hisilicon.com, catalin.marinas@arm.com 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi Marc, On 04/22/2020 01:00 PM, Marc Zyngier wrote: > 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. > > Signed-off-by: Marc Zyngier > --- > arch/arm64/include/asm/kvm_host.h | 2 +- > arch/arm64/include/asm/sysreg.h | 3 +++ > arch/arm64/kernel/cpufeature.c | 8 +++++++ > arch/arm64/kvm/reset.c | 40 ++++++++++++++++++++++++++++--- > virt/kvm/arm/arm.c | 4 +--- > 5 files changed, 50 insertions(+), 7 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 32c8a675e5a4a..7dd8fefa6aecd 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 ebc6224328318..5d10c9148e844 100644 > --- a/arch/arm64/include/asm/sysreg.h > +++ b/arch/arm64/include/asm/sysreg.h > @@ -686,6 +686,9 @@ > #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 9fac745aa7bb2..9892a845d06c9 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -208,6 +208,14 @@ 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 are not fatal. You > + * just give up KVM if PAGE_SIZE isn't supported there. Go fix > + * your favourite nesting hypervisor. > + */ > + 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), One minor issue with this is, if we get a system with cpus having values 0 and 2 (both of which indicates the stage-2 support), we might reset the value to 1 for the feature indicating, we don't support and block KVM. But, we can blame the nesting hypervisor for not emulating this to (2). Do we need a comment to make this explicit here ? Otherwise this looks fine to me Suzuki > /* > * 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 > diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c > index 30b7ea680f66c..241db35a7ef4f 100644 > --- a/arch/arm64/kvm/reset.c > +++ b/arch/arm64/kvm/reset.c > @@ -9,6 +9,7 @@ > */ > > #include > +#include > #include > #include > #include > @@ -340,11 +341,42 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu) > return ret; > } > > -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 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1); > > - parange = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1) & 0x7; > + /* > + * 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 (FIELD_GET(0xFUL << tgran_2, mmfr0)) { > + 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; > + } > + > + parange = mmfr0 & 0x7; > pa_max = id_aa64mmfr0_parange_to_phys_shift(parange); > > /* Clamp the IPA limit to the PA size supported by the kernel */ > @@ -378,6 +410,8 @@ 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 48d0ec44ad77e..53b3ba9173ba7 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) > _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm