On Thu, Jun 12, 2014 at 09:30:13AM -0700, Victor Kamensky wrote:
> Fix issue with 32bit guests running on top of BE KVM host.
> Indexes of high and low words of 64bit cp15 register are
> swapped in case of big endian code, since 64bit cp15 state is
> restored or saved with double word write or read instruction.
>
> Define helper macros to access high low words of 64bit cp15
> register.
>
> Signed-off-by: Victor Kamensky <victor.kamensky@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/kvm_host.h | 8 ++++++++
> arch/arm64/kvm/sys_regs.c | 4 ++--
> 2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 0a1d697..e9d2e11 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -140,6 +140,14 @@ struct kvm_vcpu_arch {
> #define vcpu_sys_reg(v,r) ((v)->arch.ctxt.sys_regs[(r)])
> #define vcpu_cp15(v,r) ((v)->arch.ctxt.cp15[(r)])
>
> +#ifdef CONFIG_CPU_BIG_ENDIAN
> +#define vcpu_cp15_64_high(v,r) ((v)->arch.ctxt.cp15[((r) + 0)])
> +#define vcpu_cp15_64_low(v,r) ((v)->arch.ctxt.cp15[((r) + 1)])
> +#else
> +#define vcpu_cp15_64_high(v,r) ((v)->arch.ctxt.cp15[((r) + 1)])
> +#define vcpu_cp15_64_low(v,r) ((v)->arch.ctxt.cp15[((r) + 0)])
> +#endif
> +
> struct kvm_vm_stat {
> u32 remote_tlb_flush;
> };
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 8e65e31..71aa9b0 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -137,9 +137,9 @@ static bool access_vm_reg(struct kvm_vcpu *vcpu,
> if (!p->is_aarch32) {
> vcpu_sys_reg(vcpu, r->reg) = val;
> } else {
> - vcpu_cp15(vcpu, r->reg) = val & 0xffffffffUL;
> + vcpu_cp15_64_low(vcpu, r->reg) = val & 0xffffffffUL;
> if (!p->is_32bit)
> - vcpu_cp15(vcpu, r->reg + 1) = val >> 32;
> + vcpu_cp15_64_high(vcpu, r->reg) = val >> 32;
> }
> return true;
> }
> --
> 1.8.1.4
>
I thought there was a consensus here about handling 64-bit accesses
through the 64-bit values with the vcpu_sys_reg() interface? Did you
give up on this for a particular reason?
-Christoffer
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