[PATCH 5.15 23/43] KVM: arm64: Allow indirect vectors to be used without SPECTRE_V3A

Greg Kroah-Hartman
2022-03-09T16:21:46Z

From: James Morse <james.morse@arm.com>

commit 5bdf3437603d4af87f9c7f424b0c8aeed2420745 upstream.

CPUs vulnerable to Spectre-BHB either need to make an SMC-CC firmware
call from the vectors, or run a sequence of branches. This gets added
to the hyp vectors. If there is no support for arch-workaround-1 in
firmware, the indirect vector will be used.

kvm_init_vector_slots() only initialises the two indirect slots if
the platform is vulnerable to Spectre-v3a. pKVM's hyp_map_vectors()
only initialises __hyp_bp_vect_base if the platform is vulnerable to
Spectre-v3a.

As there are about to more users of the indirect vectors, ensure
their entries in hyp_spectre_vector_selector[] are always initialised,
and __hyp_bp_vect_base defaults to the regular VA mapping.

The Spectre-v3a check is moved to a helper
kvm_system_needs_idmapped_vectors(), and merged with the code
that creates the hyp mappings.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/include/asm/kvm_host.h | 5 +++++
arch/arm64/kvm/arm.c | 5 +----
arch/arm64/kvm/hyp/nvhe/mm.c | 4 +++-
3 files changed, 9 insertions(+), 5 deletions(-)

--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -711,6 +711,11 @@ static inline void kvm_init_host_cpu_con
ctxt_sys_reg(cpu_ctxt, MPIDR_EL1) = read_cpuid_mpidr();
}

+static inline bool kvm_system_needs_idmapped_vectors(void)
+{
+ return cpus_have_const_cap(ARM64_SPECTRE_V3A);
+}
+
void kvm_arm_vcpu_ptrauth_trap(struct kvm_vcpu *vcpu);

static inline void kvm_arch_hardware_unsetup(void) {}
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1458,10 +1458,7 @@ static int kvm_init_vector_slots(void)
base = kern_hyp_va(kvm_ksym_ref(__bp_harden_hyp_vecs));
kvm_init_vector_slot(base, HYP_VECTOR_SPECTRE_DIRECT);

- if (!cpus_have_const_cap(ARM64_SPECTRE_V3A))
- return 0;
-
- if (!has_vhe()) {
+ if (kvm_system_needs_idmapped_vectors() && !has_vhe()) {
err = create_hyp_exec_mappings(__pa_symbol(__bp_harden_hyp_vecs),
__BP_HARDEN_HYP_VECS_SZ, &base);
if (err)
--- a/arch/arm64/kvm/hyp/nvhe/mm.c
+++ b/arch/arm64/kvm/hyp/nvhe/mm.c
@@ -146,8 +146,10 @@ int hyp_map_vectors(void)
phys_addr_t phys;
void *bp_base;

- if (!cpus_have_const_cap(ARM64_SPECTRE_V3A))
+ if (!kvm_system_needs_idmapped_vectors()) {
+ __hyp_bp_vect_base = __bp_harden_hyp_vecs;
return 0;
+ }

phys = __hyp_pa(__bp_harden_hyp_vecs);
bp_base = (void *)__pkvm_create_private_mapping(phys,