[PATCH v3 3/3] KVM: SVM: Add 5-level page table support for SVM

[Wei Huang <wei.huang2@amd.com>]

When the 5-level page table is enabled on host OS, the nested page table
for guest VMs must use 5-level as well. Update get_npt_level() function
to reflect this requirement. In the meanwhile, remove the code that
prevents kvm-amd driver from being loaded when 5-level page table is
detected.

Signed-off-by: Wei Huang <wei.huang2@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/svm/svm.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index b34840a2ffa7..ecc4bb8e4ea0 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -261,7 +261,9 @@ u32 svm_msrpm_offset(u32 msr)
 static int get_max_npt_level(void)
 {
 #ifdef CONFIG_X86_64
-	return PT64_ROOT_4LEVEL;
+	bool la57 = (cr4_read_shadow() & X86_CR4_LA57) != 0;
+
+	return la57 ? PT64_ROOT_5LEVEL : PT64_ROOT_4LEVEL;
 #else
 	return PT32E_ROOT_LEVEL;
 #endif
@@ -462,11 +464,6 @@ static int has_svm(void)
 		return 0;
 	}
 
-	if (pgtable_l5_enabled()) {
-		pr_info("KVM doesn't yet support 5-level paging on AMD SVM\n");
-		return 0;
-	}
-
 	return 1;
 }
 
-- 
2.31.1