[2/3] KVM: arm/arm64: fix HYP ID map extension to 52 bits

Commit Message

Kristina Martsenko Jan. 15, 2018, 3:23 p.m. UTC

Commit fa2a8445b1d3 incorrectly masks the index of the HYP ID map pgd
entry, causing a non-VHE kernel to hang during boot. This happens when
VA_BITS=48 and the ID map text is in 52-bit physical memory. In this
case we don't need an extra table level but need more entries in the
top-level table, so we need to map into hyp_pgd and need to use
__kvm_idmap_ptrs_per_pgd to mask in the extra bits. However,
__create_hyp_mappings currently masks by PTRS_PER_PGD instead.

Fix it so that we always use __kvm_idmap_ptrs_per_pgd for the HYP ID
map. This ensures that we use the larger mask for the top-level ID map
table when it has more entries. In all other cases, PTRS_PER_PGD is used
as normal.

Fixes: fa2a8445b1d3 ("arm64: allow ID map to be extended to 52 bits")
Signed-off-by: Kristina Martsenko <[e-mail]>
---
 virt/kvm/arm/mmu.c | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

Comments

Marc Zyngier Jan. 15, 2018, 6 p.m. UTC | #1

On 15/01/18 15:23, Kristina Martsenko wrote:
> Commit fa2a8445b1d3 incorrectly masks the index of the HYP ID map pgd
> entry, causing a non-VHE kernel to hang during boot. This happens when
> VA_BITS=48 and the ID map text is in 52-bit physical memory. In this
> case we don't need an extra table level but need more entries in the
> top-level table, so we need to map into hyp_pgd and need to use
> __kvm_idmap_ptrs_per_pgd to mask in the extra bits. However,
> __create_hyp_mappings currently masks by PTRS_PER_PGD instead.
> 
> Fix it so that we always use __kvm_idmap_ptrs_per_pgd for the HYP ID
> map. This ensures that we use the larger mask for the top-level ID map
> table when it has more entries. In all other cases, PTRS_PER_PGD is used
> as normal.
> 
> Fixes: fa2a8445b1d3 ("arm64: allow ID map to be extended to 52 bits")
> Signed-off-by: Kristina Martsenko <[e-mail]>

Acked-by: Marc Zyngier <[e-mail]>

	M.

Patch

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 761787befd3b..876caf531d32 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -623,21 +623,15 @@  static int create_hyp_pud_mappings(pgd_t *pgd, unsigned long start,
 	return 0;
 }
 
-static int __create_hyp_mappings(pgd_t *pgdp,
+static int __create_hyp_mappings(pgd_t *pgdp, unsigned long ptrs_per_pgd,
 				 unsigned long start, unsigned long end,
 				 unsigned long pfn, pgprot_t prot)
 {
 	pgd_t *pgd;
 	pud_t *pud;
-	unsigned long addr, next, ptrs_per_pgd = PTRS_PER_PGD;
+	unsigned long addr, next;
 	int err = 0;
 
-	/*
-	 * If it's not the hyp_pgd, fall back to the kvm idmap layout.
-	 */
-	if (pgdp != hyp_pgd)
-		ptrs_per_pgd = __kvm_idmap_ptrs_per_pgd();
-
 	mutex_lock(&kvm_hyp_pgd_mutex);
 	addr = start & PAGE_MASK;
 	end = PAGE_ALIGN(end);
@@ -705,8 +699,8 @@  int create_hyp_mappings(void *from, void *to, pgprot_t prot)
 		int err;
 
 		phys_addr = kvm_kaddr_to_phys(from + virt_addr - start);
-		err = __create_hyp_mappings(hyp_pgd, virt_addr,
-					    virt_addr + PAGE_SIZE,
+		err = __create_hyp_mappings(hyp_pgd, PTRS_PER_PGD,
+					    virt_addr, virt_addr + PAGE_SIZE,
 					    __phys_to_pfn(phys_addr),
 					    prot);
 		if (err)
@@ -737,7 +731,7 @@  int create_hyp_io_mappings(void *from, void *to, phys_addr_t phys_addr)
 	if (!is_vmalloc_addr(from) || !is_vmalloc_addr(to - 1))
 		return -EINVAL;
 
-	return __create_hyp_mappings(hyp_pgd, start, end,
+	return __create_hyp_mappings(hyp_pgd, PTRS_PER_PGD, start, end,
 				     __phys_to_pfn(phys_addr), PAGE_HYP_DEVICE);
 }
 
@@ -1743,7 +1737,7 @@  static int kvm_map_idmap_text(pgd_t *pgd)
 	int err;
 
 	/* Create the idmap in the boot page tables */
-	err = 	__create_hyp_mappings(pgd,
+	err = 	__create_hyp_mappings(pgd, __kvm_idmap_ptrs_per_pgd(),
 				      hyp_idmap_start, hyp_idmap_end,
 				      __phys_to_pfn(hyp_idmap_start),
 				      PAGE_HYP_EXEC);