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| author | Marc Zyngier <maz@kernel.org> | 2020-06-03 20:24:01 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-06-17 17:40:38 +0300 |
| commit | d96ef8fa953428fe5cf050bd3ed31ac11fb8bfe9 (patch) | |
| tree | 53a15e41f546a9db85b3d4e388305994f7477136 /virt/kvm | |
| parent | 812857678847423d44b18bdb68522f9c2e9c3dc9 (diff) | |
| download | linux-d96ef8fa953428fe5cf050bd3ed31ac11fb8bfe9.tar.xz | |
KVM: arm64: Save the host's PtrAuth keys in non-preemptible context
commit ef3e40a7ea8dbe2abd0a345032cd7d5023b9684f upstream.
When using the PtrAuth feature in a guest, we need to save the host's
keys before allowing the guest to program them. For that, we dump
them in a per-CPU data structure (the so called host context).
But both call sites that do this are in preemptible context,
which may end up in disaster should the vcpu thread get preempted
before reentering the guest.
Instead, save the keys eagerly on each vcpu_load(). This has an
increased overhead, but is at least safe.
Cc: stable@vger.kernel.org
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'virt/kvm')
| -rw-r--r-- | virt/kvm/arm/arm.c | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index 86c6aa1cb58e..986fbc3cf667 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -354,6 +354,16 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) return kvm_vgic_vcpu_init(vcpu); } +#ifdef CONFIG_ARM64 +#define __ptrauth_save_key(regs, key) \ +({ \ + regs[key ## KEYLO_EL1] = read_sysreg_s(SYS_ ## key ## KEYLO_EL1); \ + regs[key ## KEYHI_EL1] = read_sysreg_s(SYS_ ## key ## KEYHI_EL1); \ +}) +#else +#define __ptrauth_save_key(regs, key) do { } while (0) +#endif + void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) { int *last_ran; @@ -386,7 +396,17 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) else vcpu_set_wfe_traps(vcpu); - vcpu_ptrauth_setup_lazy(vcpu); + if (vcpu_has_ptrauth(vcpu)) { + struct kvm_cpu_context __maybe_unused *ctxt = vcpu->arch.host_cpu_context; + + __ptrauth_save_key(ctxt->sys_regs, APIA); + __ptrauth_save_key(ctxt->sys_regs, APIB); + __ptrauth_save_key(ctxt->sys_regs, APDA); + __ptrauth_save_key(ctxt->sys_regs, APDB); + __ptrauth_save_key(ctxt->sys_regs, APGA); + + vcpu_ptrauth_disable(vcpu); + } } void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) |