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