[PATCH v3 55/66] KVM: arm64: Allow populating S2 SW bits

Marc Zyngier
2020-12-10T16:31:23Z

The S2 page table code doesn't use the SW bits yet, but we are about
to need them to encode some guest Stage-2 information (its mapping size
in the form of the TTL encoding).

Propagate the SW bits specified by the caller, and store them into
the corresponding entry.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/include/asm/kvm_pgtable.h | 10 ++++++++++
arch/arm64/kvm/hyp/pgtable.c | 6 ++++++
2 files changed, 16 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 52ab38db04c7..90a369185702 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -35,6 +35,10 @@ struct kvm_pgtable {
* @KVM_PGTABLE_PROT_W: Write permission.
* @KVM_PGTABLE_PROT_R: Read permission.
* @KVM_PGTABLE_PROT_DEVICE: Device attributes.
+ * @KVM_PGTABLE_PROT_S2_SW0: SW bit 0.
+ * @KVM_PGTABLE_PROT_S2_SW1: SW bit 1.
+ * @KVM_PGTABLE_PROT_S2_SW2: SW bit 2.
+ * @KVM_PGTABLE_PROT_S2_SW3: SW bit 3.
*/
enum kvm_pgtable_prot {
KVM_PGTABLE_PROT_X = BIT(0),
@@ -42,6 +46,12 @@ enum kvm_pgtable_prot {
KVM_PGTABLE_PROT_R = BIT(2),

KVM_PGTABLE_PROT_DEVICE = BIT(3),
+
+ /* Cunningly, this matches the PTE bits... */
+ KVM_PGTABLE_PROT_S2_SW0 = BIT(55),
+ KVM_PGTABLE_PROT_S2_SW1 = BIT(56),
+ KVM_PGTABLE_PROT_S2_SW2 = BIT(57),
+ KVM_PGTABLE_PROT_S2_SW3 = BIT(58),
};

#define PAGE_HYP (KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W)
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 0271b4a3b9fe..9ee53e71a939 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -44,6 +44,7 @@
#define KVM_PTE_LEAF_ATTR_HI_S1_XN BIT(54)

#define KVM_PTE_LEAF_ATTR_HI_S2_XN BIT(54)
+#define KVM_PTE_LEAF_ATTR_HI_S2_SW GENMASK(58, 55)

struct kvm_pgtable_walk_data {
struct kvm_pgtable *pgt;
@@ -457,6 +458,7 @@ static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot,

attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S2_SH, sh);
attr |= KVM_PTE_LEAF_ATTR_LO_S2_AF;
+ attr |= prot & KVM_PTE_LEAF_ATTR_HI_S2_SW;
data->attr = attr;
return 0;
}
@@ -805,6 +807,10 @@ int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr,
if (prot & KVM_PGTABLE_PROT_X)
clr |= KVM_PTE_LEAF_ATTR_HI_S2_XN;

+ /* Always propagate the SW bits */
+ clr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_HI_S2_SW, 0xf);
+ set |= prot & KVM_PTE_LEAF_ATTR_HI_S2_SW;
+
ret = stage2_update_leaf_attrs(pgt, addr, 1, set, clr, NULL, &level);
if (!ret)
kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, pgt->mmu, addr, level);
--
2.29.2