On 01/02/16 13:20, Christoffer Dall wrote: > On Mon, Jan 25, 2016 at 03:53:41PM +0000, Marc Zyngier wrote: >> 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'. >> >> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> >> --- >> arch/arm64/include/asm/kvm_mmu.h | 11 ++++++++++- >> arch/arm64/kvm/hyp/hyp.h | 25 ++++++++++++++++++++++--- >> 2 files changed, 32 insertions(+), 4 deletions(-) >> >> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h >> index d3e6d7b..62f0d14 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) >> @@ -56,6 +59,8 @@ >> >> #ifdef __ASSEMBLY__ >> >> +#include <asm/alternative.h> >> +#include <asm/cpufeature.h> >> #include <asm/kvm_arm.h> >> >> .macro setup_vtcr tmp1, tmp2 >> @@ -84,7 +89,11 @@ >> * 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))) > > why do we need this casting of values instead of just defining these > inlines and calling them directly with proper typing? We commonly pass both pointers and unsigned long to this helper. Do you really want a separate helper for each type instead of one that does it all? Thanks, M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html