On Wed, May 30, 2018 at 01:47:05PM +0100, Marc Zyngier wrote:
> The {pmd,pud,pgd}_populate accessors usage in the kernel have always
> been a bit weird in KVM. We don't have a struct mm to pass (and
> neither does the kernel most of the time, but still...), and
> the 32bit code has all kind of cache maintenance that doesn't make
> sense on ARMv7+ when MP extensions are mandatory (which is the
> case when the VEs are present).
>
> Let's bite the bullet and provide our own implementations. The
> only bit of architectural code left has to do with building the table
> entry itself (arm64 having up to 52bit PA, arm lacking PUD level).
>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
> arch/arm/include/asm/kvm_mmu.h | 4 ++++
> arch/arm64/include/asm/kvm_mmu.h | 7 +++++++
> virt/kvm/arm/mmu.c | 8 +++++---
> 3 files changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> index 468ff945efa0..a94ef9833bd3 100644
> --- a/arch/arm/include/asm/kvm_mmu.h
> +++ b/arch/arm/include/asm/kvm_mmu.h
> @@ -75,6 +75,10 @@ phys_addr_t kvm_get_idmap_vector(void);
> int kvm_mmu_init(void);
> void kvm_clear_hyp_idmap(void);
>
> +#define kvm_mk_pmd(ptep) __pmd(__pa(ptep) | PMD_TYPE_TABLE)
> +#define kvm_mk_pud(pmdp) __pud(__pa(pmdp) | PMD_TYPE_TABLE)
> +#define kvm_mk_pgd(pudp) ({ BUILD_BUG(); 0; })
I can't remember how the folding logic works for ARM is a pgd entry the
entire pud table?
Assuming so:
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
> +
> static inline pte_t kvm_s2pte_mkwrite(pte_t pte)
> {
> pte_val(pte) |= L_PTE_S2_RDWR;
> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
> index 26c89b63f604..22c9f7cfdf93 100644
> --- a/arch/arm64/include/asm/kvm_mmu.h
> +++ b/arch/arm64/include/asm/kvm_mmu.h
> @@ -170,6 +170,13 @@ phys_addr_t kvm_get_idmap_vector(void);
> int kvm_mmu_init(void);
> void kvm_clear_hyp_idmap(void);
>
> +#define kvm_mk_pmd(ptep) \
> + __pmd(__phys_to_pmd_val(__pa(ptep) | PMD_TYPE_TABLE))
> +#define kvm_mk_pud(pmdp) \
> + __pud(__phys_to_pud_val(__pa(pmdp) | PMD_TYPE_TABLE))
> +#define kvm_mk_pgd(pudp) \
> + __pgd(__phys_to_pgd_val(__pa(pudp) | PUD_TYPE_TABLE))
> +
> static inline pte_t kvm_s2pte_mkwrite(pte_t pte)
> {
> pte_val(pte) |= PTE_S2_RDWR;
> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
> index c9ed239c0840..ad1980d2118a 100644
> --- a/virt/kvm/arm/mmu.c
> +++ b/virt/kvm/arm/mmu.c
> @@ -191,17 +191,19 @@ static inline void kvm_set_pmd(pmd_t *pmdp, pmd_t new_pmd)
>
> static inline void kvm_pmd_populate(pmd_t *pmdp, pte_t *ptep)
> {
> - pmd_populate_kernel(NULL, pmdp, ptep);
> + kvm_set_pmd(pmdp, kvm_mk_pmd(ptep));
> }
>
> static inline void kvm_pud_populate(pud_t *pudp, pmd_t *pmdp)
> {
> - pud_populate(NULL, pudp, pmdp);
> + WRITE_ONCE(*pudp, kvm_mk_pud(pmdp));
> + dsb(ishst);
> }
>
> static inline void kvm_pgd_populate(pgd_t *pgdp, pud_t *pudp)
> {
> - pgd_populate(NULL, pgdp, pudp);
> + WRITE_ONCE(*pgdp, kvm_mk_pgd(pudp));
> + dsb(ishst);
> }
>
> /*
> --
> 2.17.1
>
