KVM: arm64: Enable access to sanitized CPU features at EL2

Introduce the infrastructure in KVM enabling to copy CPU feature
registers into EL2-owned data-structures, to allow reading sanitised
values directly at EL2 in nVHE.

Given that only a subset of these features are being read by the
hypervisor, the ones that need to be copied are to be listed under
<asm/kvm_cpufeature.h> together with the name of the nVHE variable that
will hold the copy. This introduces only the infrastructure enabling
this copy. The first users will follow shortly.

Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-14-qperret@google.com

1 files changed, 19 insertions, 0 deletions

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 4f2f1e3145de..6c5d133689ae 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -21,6 +21,7 @@
 #include <asm/debug-monitors.h>
 #include <asm/esr.h>
 #include <asm/kvm_arm.h>
+#include <asm/kvm_cpufeature.h>
 #include <asm/kvm_emulate.h>
 #include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
@@ -2775,3 +2776,21 @@ void kvm_sys_reg_table_init(void)
 	/* Clear all higher bits. */
 	cache_levels &= (1 << (i*3))-1;
 }
+
+#define CPU_FTR_REG_HYP_COPY(id, name) \
+	{ .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) }
+struct __ftr_reg_copy_entry {
+	u32			sys_id;
+	struct arm64_ftr_reg	*dst;
+} hyp_ftr_regs[] __initdata = {
+};
+
+void __init setup_kvm_el2_caps(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(hyp_ftr_regs); i++) {
+		WARN(copy_ftr_reg(hyp_ftr_regs[i].sys_id, hyp_ftr_regs[i].dst),
+		     "%u feature register not found\n", hyp_ftr_regs[i].sys_id);
+	}
+}