arm64: KVM: VHE: Patch out kern_hyp_va
The kern_hyp_va macro is pretty meaninless with VHE, as there is
only one mapping - the kernel one.
In order to keep the code readable and efficient, use runtime
patching to replace the 'and' instruction used to compute the VA
with a 'nop'.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 7364339..9a9318a 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -23,13 +23,16 @@
#include <asm/cpufeature.h>
/*
- * As we only have the TTBR0_EL2 register, we cannot express
+ * As ARMv8.0 only has the TTBR0_EL2 register, we cannot express
* "negative" addresses. This makes it impossible to directly share
* mappings with the kernel.
*
* Instead, give the HYP mode its own VA region at a fixed offset from
* the kernel by just masking the top bits (which are all ones for a
* kernel address).
+ *
+ * ARMv8.1 (using VHE) does have a TTBR1_EL2, and doesn't use these
+ * macros (the entire kernel runs at EL2).
*/
#define HYP_PAGE_OFFSET_SHIFT VA_BITS
#define HYP_PAGE_OFFSET_MASK ((UL(1) << HYP_PAGE_OFFSET_SHIFT) - 1)
@@ -56,12 +59,19 @@
#ifdef __ASSEMBLY__
+#include <asm/alternative.h>
+#include <asm/cpufeature.h>
+
/*
* Convert a kernel VA into a HYP VA.
* reg: VA to be converted.
*/
.macro kern_hyp_va reg
+alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
and \reg, \reg, #HYP_PAGE_OFFSET_MASK
+alternative_else
+ nop
+alternative_endif
.endm
#else