[PATCH v2 5/6] KVM: arm/arm64: Stop using {pmd,pud,pgd}_populate

Marc Zyngier
2018-05-30T12:47:05Z

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@arm.com>
---
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; })
+
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