arm64: alternatives: kvm: prepare for cap changes

The KVM patching callbacks use cpus_have_final_cap() internally within
has_vhe(), and subsequent patches will make it invalid to call
cpus_have_final_cap() before alternatives patching has completed, and
will mean that cpus_have_const_cap() will always fall back to dynamic
checks prior to alternatives patching.

In preparation for said change, this patch modifies the KVM patching
callbacks to use cpus_have_cap() directly. This is not subject to
patching, and will dynamically check the cpu_hwcaps array, which is
functionally equivalent to the existing behaviour.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220912162210.3626215-3-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/kvm/va_layout.c b/arch/arm64/kvm/va_layout.c
index acdb7b3cc97d65aaa9a540ea3773e46af1ea04cf..91b22a014610b22ffcc2883c9b499151d8e77f26 100644 (file)
--- a/arch/arm64/kvm/va_layout.c
+++ b/arch/arm64/kvm/va_layout.c
@@ -169,7 +169,7 @@ void __init kvm_update_va_mask(struct alt_instr *alt,
                 * dictates it and we don't have any spare bits in the
                 * address), NOP everything after masking the kernel VA.
                 */
-               if (has_vhe() || (!tag_val && i > 0)) {
+               if (cpus_have_cap(ARM64_HAS_VIRT_HOST_EXTN) || (!tag_val && i > 0)) {
                        updptr[i] = cpu_to_le32(aarch64_insn_gen_nop());
                        continue;
                }
@@ -193,7 +193,8 @@ void kvm_patch_vector_branch(struct alt_instr *alt,
 
        BUG_ON(nr_inst != 4);
 
-       if (!cpus_have_const_cap(ARM64_SPECTRE_V3A) || WARN_ON_ONCE(has_vhe()))
+       if (!cpus_have_cap(ARM64_SPECTRE_V3A) ||
+           WARN_ON_ONCE(cpus_have_cap(ARM64_HAS_VIRT_HOST_EXTN)))
                return;
 
        /*