[PATCH v4 08/23] arm64: KVM: VHE: Patch out kern_hyp_va
From: Marc Zyngier <hidden>
Date: 2016-02-11 18:40:26
Also in:
kvm, kvmarm, lkml
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
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 <redacted> Signed-off-by: Marc Zyngier <redacted> --- arch/arm64/include/asm/kvm_mmu.h | 12 +++++++++++- arch/arm64/kvm/hyp/hyp.h | 25 ++++++++++++++++++++++--- 2 files changed, 33 insertions(+), 4 deletions(-)
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
diff --git a/arch/arm64/kvm/hyp/hyp.h b/arch/arm64/kvm/hyp/hyp.h
index fb27517..fc502f3 100644
--- a/arch/arm64/kvm/hyp/hyp.h
+++ b/arch/arm64/kvm/hyp/hyp.h@@ -25,9 +25,28 @@ #define __hyp_text __section(.hyp.text) notrace -#define kern_hyp_va(v) (typeof(v))((unsigned long)(v) & HYP_PAGE_OFFSET_MASK) -#define hyp_kern_va(v) (typeof(v))((unsigned long)(v) - HYP_PAGE_OFFSET \ - + PAGE_OFFSET) +static inline unsigned long __kern_hyp_va(unsigned long v) +{ + asm volatile(ALTERNATIVE("and %0, %0, %1", + "nop", + ARM64_HAS_VIRT_HOST_EXTN) + : "+r" (v) : "i" (HYP_PAGE_OFFSET_MASK)); + return v; +} + +#define kern_hyp_va(v) (typeof(v))(__kern_hyp_va((unsigned long)(v))) + +static inline unsigned long __hyp_kern_va(unsigned long v) +{ + u64 offset = PAGE_OFFSET - HYP_PAGE_OFFSET; + asm volatile(ALTERNATIVE("add %0, %0, %1", + "nop", + ARM64_HAS_VIRT_HOST_EXTN) + : "+r" (v) : "r" (offset)); + return v; +} + +#define hyp_kern_va(v) (typeof(v))(__hyp_kern_va((unsigned long)(v))) /** * hyp_alternate_select - Generates patchable code sequences that are
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2.1.4