[PATCH] arm64/cpufeature: Verify KVM capabilities during CPU hotplug

Anshuman Khandual
2020-05-07T06:20:39Z

This validates KVM capabilities like VMID width, IPA range for hotplug CPU
against system finalized values. While here, it factors out get_vmid_bits()
for general use and also defines ID_AA64MMFR0_PARANGE_MASK.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: kvmarm@lists.cs.columbia.edu
Cc: linux-kernel@vger.kernel.org

Suggested-by: Suzuki Poulose <suzuki.poulose@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
arch/arm64/include/asm/cpufeature.h | 22 +++++++++++++++++++
arch/arm64/include/asm/kvm_mmu.h | 2 +-
arch/arm64/include/asm/sysreg.h | 1 +
arch/arm64/kernel/cpufeature.c | 2 ++
arch/arm64/kvm/reset.c | 33 +++++++++++++++++++++++++++--
5 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index afe08251ff95..6808a2091de4 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -745,6 +745,28 @@ static inline bool cpu_has_hw_af(void)
extern bool cpu_has_amu_feat(int cpu);
#endif

+static inline unsigned int get_vmid_bits(u64 mmfr1)
+{
+ int vmid_bits;
+
+ vmid_bits = cpuid_feature_extract_unsigned_field(mmfr1,
+ ID_AA64MMFR1_VMIDBITS_SHIFT);
+ if (vmid_bits == ID_AA64MMFR1_VMIDBITS_16)
+ return 16;
+
+ /*
+ * Return the default here even if any reserved
+ * value is fetched from the system register.
+ */
+ return 8;
+}
+
+#ifdef CONFIG_KVM_ARM_HOST
+void verify_kvm_capabilities(void);
+#else
+static inline void verify_kvm_capabilities(void) { }
+#endif
+
#endif /* __ASSEMBLY__ */

#endif
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 30b0e8d6b895..a7137e144b97 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -416,7 +416,7 @@ static inline unsigned int kvm_get_vmid_bits(void)
{
int reg = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);

- return (cpuid_feature_extract_unsigned_field(reg, ID_AA64MMFR1_VMIDBITS_SHIFT) == 2) ? 16 : 8;
+ return get_vmid_bits(reg);
}

/*
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index c4ac0ac25a00..3510a4668970 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -705,6 +705,7 @@
#define ID_AA64MMFR0_TGRAN16_SUPPORTED 0x1
#define ID_AA64MMFR0_PARANGE_48 0x5
#define ID_AA64MMFR0_PARANGE_52 0x6
+#define ID_AA64MMFR0_PARANGE_MASK 0x7

#ifdef CONFIG_ARM64_PA_BITS_52
#define ID_AA64MMFR0_PARANGE_MAX ID_AA64MMFR0_PARANGE_52
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 9fac745aa7bb..041dd610b0f8 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -2206,6 +2206,8 @@ static void verify_local_cpu_capabilities(void)

if (system_supports_sve())
verify_sve_features();
+
+ verify_kvm_capabilities();
}

void check_local_cpu_capabilities(void)
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 30b7ea680f66..1eebcc2a8396 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -340,11 +340,39 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
return ret;
}

+void verify_kvm_capabilities(void)
+{
+ u64 safe_mmfr1, mmfr0, mmfr1;
+ int parange, ipa_max;
+ unsigned int safe_vmid_bits, vmid_bits;
+
+ safe_mmfr1 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);
+ mmfr0 = read_cpuid(ID_AA64MMFR0_EL1);
+ mmfr1 = read_cpuid(ID_AA64MMFR1_EL1);
+
+ /* Verify VMID bits */
+ safe_vmid_bits = get_vmid_bits(safe_mmfr1);
+ vmid_bits = get_vmid_bits(mmfr1);
+ if (vmid_bits < safe_vmid_bits) {
+ pr_crit("CPU%d: VMID width mismatch\n", smp_processor_id());
+ cpu_die_early();
+ }
+
+ /* Verify IPA range */
+ parange = mmfr0 & ID_AA64MMFR0_PARANGE_MASK;
+ ipa_max = id_aa64mmfr0_parange_to_phys_shift(parange);
+ if (ipa_max < kvm_ipa_limit) {
+ pr_crit("CPU%d: IPA range mismatch\n", smp_processor_id());
+ cpu_die_early();
+ }
+}
+
void kvm_set_ipa_limit(void)
{
unsigned int ipa_max, pa_max, va_max, parange;

- parange = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1) & 0x7;
+ parange = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1) &
+ ID_AA64MMFR0_PARANGE_MASK;
pa_max = id_aa64mmfr0_parange_to_phys_shift(parange);

/* Clamp the IPA limit to the PA size supported by the kernel */
@@ -406,7 +434,8 @@ int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type)
phys_shift = KVM_PHYS_SHIFT;
}

- parange = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1) & 7;
+ parange = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1) &
+ ID_AA64MMFR0_PARANGE_MASK;
if (parange > ID_AA64MMFR0_PARANGE_MAX)
parange = ID_AA64MMFR0_PARANGE_MAX;
vtcr |= parange << VTCR_EL2_PS_SHIFT;
--
2.20.1