lguest: add infrastructure to check mappings.
We normally abort the guest unconditionally when it gives us a bad address,
but in the next patch we want to copy some bytes which may not be mapped.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c
index e8b55c3..69c35ca 100644
--- a/drivers/lguest/page_tables.c
+++ b/drivers/lguest/page_tables.c
@@ -647,7 +647,7 @@
/*:*/
/* We walk down the guest page tables to get a guest-physical address */
-unsigned long guest_pa(struct lg_cpu *cpu, unsigned long vaddr)
+bool __guest_pa(struct lg_cpu *cpu, unsigned long vaddr, unsigned long *paddr)
{
pgd_t gpgd;
pte_t gpte;
@@ -656,31 +656,47 @@
#endif
/* Still not set up? Just map 1:1. */
- if (unlikely(cpu->linear_pages))
- return vaddr;
+ if (unlikely(cpu->linear_pages)) {
+ *paddr = vaddr;
+ return true;
+ }
/* First step: get the top-level Guest page table entry. */
gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t);
/* Toplevel not present? We can't map it in. */
- if (!(pgd_flags(gpgd) & _PAGE_PRESENT)) {
- kill_guest(cpu, "Bad address %#lx", vaddr);
- return -1UL;
- }
+ if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
+ goto fail;
#ifdef CONFIG_X86_PAE
gpmd = lgread(cpu, gpmd_addr(gpgd, vaddr), pmd_t);
- if (!(pmd_flags(gpmd) & _PAGE_PRESENT)) {
- kill_guest(cpu, "Bad address %#lx", vaddr);
- return -1UL;
- }
+ if (!(pmd_flags(gpmd) & _PAGE_PRESENT))
+ goto fail;
gpte = lgread(cpu, gpte_addr(cpu, gpmd, vaddr), pte_t);
#else
gpte = lgread(cpu, gpte_addr(cpu, gpgd, vaddr), pte_t);
#endif
if (!(pte_flags(gpte) & _PAGE_PRESENT))
- kill_guest(cpu, "Bad address %#lx", vaddr);
+ goto fail;
- return pte_pfn(gpte) * PAGE_SIZE | (vaddr & ~PAGE_MASK);
+ *paddr = pte_pfn(gpte) * PAGE_SIZE | (vaddr & ~PAGE_MASK);
+ return true;
+
+fail:
+ *paddr = -1UL;
+ return false;
+}
+
+/*
+ * This is the version we normally use: kills the Guest if it uses a
+ * bad address
+ */
+unsigned long guest_pa(struct lg_cpu *cpu, unsigned long vaddr)
+{
+ unsigned long paddr;
+
+ if (!__guest_pa(cpu, vaddr, &paddr))
+ kill_guest(cpu, "Bad address %#lx", vaddr);
+ return paddr;
}
/*