arm64: KVM: Add HYP per-cpu accessors

As we're going to require to access per-cpu variables at EL2,
let's craft the minimum set of accessors required to implement
reading a per-cpu variable, relying on tpidr_el2 to contain the
per-cpu offset.

Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 25 insertions, 2 deletions

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index f6648a3e4152..fefd8cf42c35 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -71,14 +71,37 @@ extern u32 __kvm_get_mdcr_el2(void);
 
 extern u32 __init_stage2_translation(void);
 
+/* Home-grown __this_cpu_{ptr,read} variants that always work at HYP */
+#define __hyp_this_cpu_ptr(sym)                                         \
+        ({                                                              \
+                void *__ptr = hyp_symbol_addr(sym);                     \
+                __ptr += read_sysreg(tpidr_el2);                        \
+                (typeof(&sym))__ptr;                                    \
+         })
+
+#define __hyp_this_cpu_read(sym)                                        \
+        ({                                                              \
+                *__hyp_this_cpu_ptr(sym);                               \
+         })
+
 #else /* __ASSEMBLY__ */
 
-.macro get_host_ctxt reg, tmp
-        adr_l   \reg, kvm_host_cpu_state
+.macro hyp_adr_this_cpu reg, sym, tmp
+        adr_l   \reg, \sym
         mrs     \tmp, tpidr_el2
         add     \reg, \reg, \tmp
 .endm
 
+.macro hyp_ldr_this_cpu reg, sym, tmp
+        adr_l   \reg, \sym
+        mrs     \tmp, tpidr_el2
+        ldr     \reg,  [\reg, \tmp]
+.endm
+
+.macro get_host_ctxt reg, tmp
+        hyp_adr_this_cpu \reg, kvm_host_cpu_state, \tmp
+.endm
+
 .macro get_vcpu_ptr vcpu, ctxt
         get_host_ctxt \ctxt, \vcpu
         ldr     \vcpu, [\ctxt, #HOST_CONTEXT_VCPU]