arm64/cpufeature: Validate hypervisor capabilities during CPU hotplug

This validates hypervisor capabilities like VMID width, IPA range for any
hot plug CPU against system finalized values. KVM's view of the IPA space
is used while allowing a given CPU to come up. While here, it factors out
get_vmid_bits() for general use.

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>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1589248647-22925-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index f5c4672..928814d 100644 (file)
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -752,6 +752,24 @@ 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;
+}
+
+u32 get_kvm_ipa_limit(void);
+
 #endif /* __ASSEMBLY__ */
 
 #endif

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 30b0e8d..a7137e1 100644 (file)
--- 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/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 9b05843..be8a634 100644 (file)
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -2315,6 +2315,35 @@ static void verify_sve_features(void)
        /* Add checks on other ZCR bits here if necessary */
 }
 
+static void verify_hyp_capabilities(void)
+{
+       u64 safe_mmfr1, mmfr0, mmfr1;
+       int parange, ipa_max;
+       unsigned int safe_vmid_bits, vmid_bits;
+
+       if (!IS_ENABLED(CONFIG_KVM) || !IS_ENABLED(CONFIG_KVM_ARM_HOST))
+               return;
+
+       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 & 0x7;
+       ipa_max = id_aa64mmfr0_parange_to_phys_shift(parange);
+       if (ipa_max < get_kvm_ipa_limit()) {
+               pr_crit("CPU%d: IPA range mismatch\n", smp_processor_id());
+               cpu_die_early();
+       }
+}
 
 /*
  * Run through the enabled system capabilities and enable() it on this CPU.
@@ -2340,6 +2369,9 @@ static void verify_local_cpu_capabilities(void)
 
        if (system_supports_sve())
                verify_sve_features();
+
+       if (is_hyp_mode_available())
+               verify_hyp_capabilities();
 }
 
 void check_local_cpu_capabilities(void)

diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 102e5c4..d4eb661 100644 (file)
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -332,6 +332,11 @@ out:
        return ret;
 }
 
+u32 get_kvm_ipa_limit(void)
+{
+       return kvm_ipa_limit;
+}
+
 void kvm_set_ipa_limit(void)
 {
        unsigned int ipa_max, pa_max, va_max, parange;