KVM: x86/mmu: Drop KVM's hugepage enums in favor of the kernel's enums

Replace KVM's PT_PAGE_TABLE_LEVEL, PT_DIRECTORY_LEVEL and PT_PDPE_LEVEL
with the kernel's PG_LEVEL_4K, PG_LEVEL_2M and PG_LEVEL_1G.  KVM's
enums are borderline impossible to remember and result in code that is
visually difficult to audit, e.g.

        if (!enable_ept)
                ept_lpage_level = 0;
        else if (cpu_has_vmx_ept_1g_page())
                ept_lpage_level = PT_PDPE_LEVEL;
        else if (cpu_has_vmx_ept_2m_page())
                ept_lpage_level = PT_DIRECTORY_LEVEL;
        else
                ept_lpage_level = PT_PAGE_TABLE_LEVEL;

versus

        if (!enable_ept)
                ept_lpage_level = 0;
        else if (cpu_has_vmx_ept_1g_page())
                ept_lpage_level = PG_LEVEL_1G;
        else if (cpu_has_vmx_ept_2m_page())
                ept_lpage_level = PG_LEVEL_2M;
        else
                ept_lpage_level = PG_LEVEL_4K;

No functional change intended.

Suggested-by: Barret Rhoden <brho@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200428005422.4235-4-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -110,14 +110,8 @@
 #define UNMAPPED_GVA (~(gpa_t)0)
 
 /* KVM Hugepage definitions for x86 */
-enum {
-	PT_PAGE_TABLE_LEVEL   = 1,
-	PT_DIRECTORY_LEVEL    = 2,
-	PT_PDPE_LEVEL         = 3,
-};
-#define KVM_MAX_HUGEPAGE_LEVEL	PT_PDPE_LEVEL
-#define KVM_NR_PAGE_SIZES	(KVM_MAX_HUGEPAGE_LEVEL - \
-				 PT_PAGE_TABLE_LEVEL + 1)
+#define KVM_MAX_HUGEPAGE_LEVEL	PG_LEVEL_1G
+#define KVM_NR_PAGE_SIZES	(KVM_MAX_HUGEPAGE_LEVEL - PG_LEVEL_4K + 1)
 #define KVM_HPAGE_GFN_SHIFT(x)	(((x) - 1) * 9)
 #define KVM_HPAGE_SHIFT(x)	(PAGE_SHIFT + KVM_HPAGE_GFN_SHIFT(x))
 #define KVM_HPAGE_SIZE(x)	(1UL << KVM_HPAGE_SHIFT(x))
@@ -126,7 +120,7 @@ enum {
 
 static inline gfn_t gfn_to_index(gfn_t gfn, gfn_t base_gfn, int level)
 {
-	/* KVM_HPAGE_GFN_SHIFT(PT_PAGE_TABLE_LEVEL) must be 0. */
+	/* KVM_HPAGE_GFN_SHIFT(PG_LEVEL_4K) must be 0. */
 	return (gfn >> KVM_HPAGE_GFN_SHIFT(level)) -
 		(base_gfn >> KVM_HPAGE_GFN_SHIFT(level));
 }