lkml.org 
[lkml]   [2016]   [Jan]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v2 07/21] arm64: KVM: VHE: Patch out kern_hyp_va
    Date
    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@arm.com>
    ---
    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)))

    /**
    * hyp_alternate_select - Generates patchable code sequences that are
    --
    2.1.4
    \
     
     \ /
      Last update: 2016-01-25 17:41    [W:4.082 / U:0.108 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site