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? -Christoffer > > /** > * hyp_alternate_select - Generates patchable code sequences that are > -- > 2.1.4 > -- 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