On Wed, Mar 17, 2021 at 02:17:13PM +0000, Quentin Perret wrote:
> In order to further configure stage-2 page-tables, pass flags to the
> init function using a new enum.
>
> The first of these flags allows to disable FWB even if the hardware
> supports it as we will need to do so for the host stage-2.
>
> Signed-off-by: Quentin Perret <qper...@google.com>
>
> ---
>
> One question is, do we want to use stage2_has_fwb() everywhere, including
> guest-specific paths (e.g. kvm_arch_prepare_memory_region(), ...) ?
>
> That'd make this patch more intrusive, but would make the whole codebase
> work with FWB enabled on a guest by guest basis. I don't see us use that
> anytime soon (other than maybe debug of some sort?) but it'd be good to
> have an agreement.
I don't see the value in spreading this everywhere for now.
> arch/arm64/include/asm/kvm_pgtable.h | 19 +++++++++--
> arch/arm64/include/asm/pgtable-prot.h | 4 +--
> arch/arm64/kvm/hyp/pgtable.c | 49 +++++++++++++++++----------
> 3 files changed, 50 insertions(+), 22 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_pgtable.h
> b/arch/arm64/include/asm/kvm_pgtable.h
> index b93a2a3526ab..7382bdfb6284 100644
> --- a/arch/arm64/include/asm/kvm_pgtable.h
> +++ b/arch/arm64/include/asm/kvm_pgtable.h
> @@ -56,6 +56,15 @@ struct kvm_pgtable_mm_ops {
> phys_addr_t (*virt_to_phys)(void *addr);
> };
>
> +/**
> + * enum kvm_pgtable_stage2_flags - Stage-2 page-table flags.
> + * @KVM_PGTABLE_S2_NOFWB: Don't enforce Normal-WB even if the CPUs have
> + * ARM64_HAS_STAGE2_FWB.
> + */
> +enum kvm_pgtable_stage2_flags {
> + KVM_PGTABLE_S2_NOFWB = BIT(0),
> +};
> +
> /**
> * struct kvm_pgtable - KVM page-table.
> * @ia_bits: Maximum input address size, in bits.
> @@ -72,6 +81,7 @@ struct kvm_pgtable {
>
> /* Stage-2 only */
> struct kvm_s2_mmu *mmu;
> + enum kvm_pgtable_stage2_flags flags;
> };
>
> /**
> @@ -201,11 +211,16 @@ u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift);
> * @arch: Arch-specific KVM structure representing the guest virtual
> * machine.
> * @mm_ops: Memory management callbacks.
> + * @flags: Stage-2 configuration flags.
> *
> * Return: 0 on success, negative error code on failure.
> */
> -int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_arch *arch,
> - struct kvm_pgtable_mm_ops *mm_ops);
> +int kvm_pgtable_stage2_init_flags(struct kvm_pgtable *pgt, struct kvm_arch
> *arch,
> + struct kvm_pgtable_mm_ops *mm_ops,
> + enum kvm_pgtable_stage2_flags flags);
> +
> +#define kvm_pgtable_stage2_init(pgt, arch, mm_ops) \
> + kvm_pgtable_stage2_init_flags(pgt, arch, mm_ops, 0)
nit: I think some of the kerneldoc refers to "kvm_pgtable_stage_init()"
so that needs a trivial update to e.g. "kvm_pgtable_stage_init*()".
> diff --git a/arch/arm64/include/asm/pgtable-prot.h
> b/arch/arm64/include/asm/pgtable-prot.h
> index 046be789fbb4..beeb722a82d3 100644
> --- a/arch/arm64/include/asm/pgtable-prot.h
> +++ b/arch/arm64/include/asm/pgtable-prot.h
> @@ -72,10 +72,10 @@ extern bool arm64_use_ng_mappings;
> #define PAGE_KERNEL_EXEC __pgprot(PROT_NORMAL & ~PTE_PXN)
> #define PAGE_KERNEL_EXEC_CONT __pgprot((PROT_NORMAL & ~PTE_PXN) |
> PTE_CONT)
>
> -#define PAGE_S2_MEMATTR(attr)
> \
> +#define PAGE_S2_MEMATTR(attr, has_fwb)
> \
> ({ \
> u64 __val; \
> - if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB)) \
> + if (has_fwb) \
> __val = PTE_S2_MEMATTR(MT_S2_FWB_ ## attr); \
> else \
> __val = PTE_S2_MEMATTR(MT_S2_ ## attr); \
Can you take the pgt structure instead of a bool here, or does it end up
being really ugly?
Will
