Re: [PATCH v4] arm64: fix VTTBR_BADDR_MASK

[Joel Schopp <joel.schopp@amd.com>]

 #endif /* __ARM_KVM_MMU_H__ */
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 16e7994..70f0f02 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -521,6 +521,7 @@ int create_hyp_io_mappings(void *from, void *to, phys_addr_t phys_addr)
  */
 int kvm_alloc_stage2_pgd(struct kvm *kvm)
 {
+	unsigned int s2_pgds, s2_pgd_order;
 	pgd_t *pgd;
 
 	if (kvm->arch.pgd != NULL) {
@@ -528,10 +529,18 @@ int kvm_alloc_stage2_pgd(struct kvm *kvm)
 		return -EINVAL;
 	}
 
-	pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, S2_PGD_ORDER);
+	s2_pgds = (1 << (kvm_get_phys_addr_shift() - PGDIR_SHIFT));
+	s2_pgd_order = get_order(s2_pgds * sizeof(pgd_t));
+
+	pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, s2_pgd_order);
 	if (!pgd)
 		return -ENOMEM;
 
+	if ((unsigned long)pgd & ~vttbr_baddr_mask) {
+		kvm_err("Stage-2 pgd not correctly aligned: %p\n", pgd);
+		return -EFAULT;
+	}


There are two problems that I've found here.  The first problem is that
vttbr_baddr_mask isn't allocated yet at this point in the code.  The
second problem is that pgd is a virtual address, ie pgd ==
0xfffffe03bbb40000 while the vttbr masks off the high bits for a
physical address, ie vttbr_baddr_mask=0x00007ffffffe0000 .  Even
correcting for those issues I haven't been able to make this check work
properly.  I'll resend v5 the patch with all the other suggested changes.