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KVM: arm64: Add ARM64_KVM_PROTECTED_MODE CPU capability

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Expose the boolean value whether the system is running with KVM in
protected mode (nVHE + kernel param). CPU capability was selected over
a global variable to allow use in alternatives.

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201202184122.26046-3-dbrazdil@google.com
This commit is contained in:
David Brazdil 2020-12-02 18:40:58 +00:00 committed by Marc Zyngier
parent d8b369c4e3
commit 3eb681fba2
5 changed files with 41 additions and 2 deletions
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3
arch/arm64/include/asm/cpucaps.h
View File

@ -65,7 +65,8 @@
#define ARM64_MTE 57
#define ARM64_WORKAROUND_1508412 58
#define ARM64_HAS_LDAPR 59
#define ARM64_KVM_PROTECTED_MODE 60
#define ARM64_NCAPS 60
#define ARM64_NCAPS 61
#endif /* __ASM_CPUCAPS_H */

1
arch/arm64/include/asm/kvm_host.h
View File

@ -58,6 +58,7 @@ enum kvm_mode {
KVM_MODE_DEFAULT,
KVM_MODE_PROTECTED,
};
enum kvm_mode kvm_get_mode(void);
DECLARE_STATIC_KEY_FALSE(userspace_irqchip_in_use);

8
arch/arm64/include/asm/virt.h
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@ -97,6 +97,14 @@ static __always_inline bool has_vhe(void)
return cpus_have_final_cap(ARM64_HAS_VIRT_HOST_EXTN);
}
static __always_inline bool is_protected_kvm_enabled(void)
{
if (is_vhe_hyp_code())
return false;
else
return cpus_have_final_cap(ARM64_KVM_PROTECTED_MODE);
}
#endif /* __ASSEMBLY__ */
#endif /* ! __ASM__VIRT_H */

22
arch/arm64/kernel/cpufeature.c
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@ -74,6 +74,7 @@
#include <asm/cpufeature.h>
#include <asm/cpu_ops.h>
#include <asm/fpsimd.h>
#include <asm/kvm_host.h>
#include <asm/mmu_context.h>
#include <asm/mte.h>
#include <asm/processor.h>
@ -1703,6 +1704,21 @@ static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap)
}
#endif /* CONFIG_ARM64_MTE */
#ifdef CONFIG_KVM
static bool is_kvm_protected_mode(const struct arm64_cpu_capabilities *entry, int __unused)
{
if (kvm_get_mode() != KVM_MODE_PROTECTED)
return false;
if (is_kernel_in_hyp_mode()) {
pr_warn("Protected KVM not available with VHE\n");
return false;
}
return true;
}
#endif /* CONFIG_KVM */
/* Internal helper functions to match cpu capability type */
static bool
cpucap_late_cpu_optional(const struct arm64_cpu_capabilities *cap)
@ -1794,6 +1810,12 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.field_pos = ID_AA64PFR0_EL1_SHIFT,
.min_field_value = ID_AA64PFR0_EL1_32BIT_64BIT,
},
{
.desc = "Protected KVM",
.capability = ARM64_KVM_PROTECTED_MODE,
.type = ARM64_CPUCAP_SYSTEM_FEATURE,
.matches = is_kvm_protected_mode,
},
#endif
{
.desc = "Kernel page table isolation (KPTI)",

9
arch/arm64/kvm/arm.c
View File

@ -1771,7 +1771,9 @@ int kvm_arch_init(void *opaque)
if (err)
goto out_hyp;
if (in_hyp_mode)
if (is_protected_kvm_enabled())
kvm_info("Protected nVHE mode initialized successfully\n");
else if (in_hyp_mode)
kvm_info("VHE mode initialized successfully\n");
else
kvm_info("Hyp mode initialized successfully\n");
@ -1806,6 +1808,11 @@ static int __init early_kvm_mode_cfg(char *arg)
}
early_param("kvm-arm.mode", early_kvm_mode_cfg);
enum kvm_mode kvm_get_mode(void)
{
return kvm_mode;
}
static int arm_init(void)
{
int rc = kvm_init(NULL, sizeof(struct kvm_vcpu), 0, THIS_MODULE);