On Thursday 11 Mar 2021 at 19:36:39 (+0000), Will Deacon wrote:
> On Wed, Mar 10, 2021 at 05:57:30PM +0000, Quentin Perret wrote:
> > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> > index 066030717a4c..f2d8b479ff74 100644
> > --- a/arch/arm64/kernel/cpufeature.c
> > +++ b/arch/arm64/kernel/cpufeature.c
> > @@ -1154,6 +1154,18 @@ u64 read_sanitised_ftr_reg(u32 id)
> > }
> > EXPORT_SYMBOL_GPL(read_sanitised_ftr_reg);
> >
> > +int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst)
> > +{
> > + struct arm64_ftr_reg *regp = get_arm64_ftr_reg(id);
> > +
> > + if (!regp)
> > + return -EINVAL;
> > +
> > + memcpy(dst, regp, sizeof(*regp));
>
> Can you not just use struct assignment here?
Sure.
> > diff --git a/arch/arm64/kvm/hyp/nvhe/cache.S b/arch/arm64/kvm/hyp/nvhe/cache.S
> > new file mode 100644
> > index 000000000000..36cef6915428
> > --- /dev/null
> > +++ b/arch/arm64/kvm/hyp/nvhe/cache.S
> > @@ -0,0 +1,13 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Code copied from arch/arm64/mm/cache.S.
> > + */
> > +
> > +#include <linux/linkage.h>
> > +#include <asm/assembler.h>
> > +#include <asm/alternative.h>
> > +
> > +SYM_FUNC_START_PI(__flush_dcache_area)
> > + dcache_by_line_op civac, sy, x0, x1, x2, x3
> > + ret
> > +SYM_FUNC_END_PI(__flush_dcache_area)
>
> Separate patch for this? (or fold it into that one really near the start
> that introduces some other PI helpers).
Right, I guess that'll make reverts and such easier so why not.
> > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> > index 4f2f1e3145de..84be93df52fa 100644
> > --- a/arch/arm64/kvm/sys_regs.c
> > +++ b/arch/arm64/kvm/sys_regs.c
> > @@ -21,6 +21,7 @@
> > #include <asm/debug-monitors.h>
> > #include <asm/esr.h>
> > #include <asm/kvm_arm.h>
> > +#include <asm/kvm_cpufeature.h>
> > #include <asm/kvm_emulate.h>
> > #include <asm/kvm_hyp.h>
> > #include <asm/kvm_mmu.h>
> > @@ -2775,3 +2776,23 @@ void kvm_sys_reg_table_init(void)
> > /* Clear all higher bits. */
> > cache_levels &= (1 << (i*3))-1;
> > }
> > +
> > +#undef KVM_HYP_CPU_FTR_REG
> > +#define KVM_HYP_CPU_FTR_REG(id, name) \
> > + { .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) },
> > +struct __ftr_reg_copy_entry {
> > + u32 sys_id;
> > + struct arm64_ftr_reg *dst;
> > +} hyp_ftr_regs[] __initdata = {
> > + #include <asm/kvm_cpufeature.h>
> > +};
>
> This looks a bit elaborate to me. Why can't you just spell things out here
> like:
>
> #define KVM_HYP_CPU_FTR_REG(id, name) \
> { .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) }
>
> struct __ftr_reg_copy_entry {
> u32 sys_id;
> struct arm64_ftr_reg *dst;
> } hyp_ftr_regs[] __initdata = {
> KVM_HYP_CPU_FTR_REG(SYS_CTR_EL0, arm64_ftr_reg_ctrel0),
> ...
> };
>
> and then have the header file be a normal, guarded header which just
> declares these things? The id parameter to the macro isn't used there.
I just tried to reduce the boilerplate as much as possible -- in the
current form you only need to add additional features to the header
it'll 'just work'.
Thanks,
Quentin
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