KVM: SVM: Add 5-level page table support for SVM

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>
Message-Id: <20210818165549.3771014-4-wei.huang2@amd.com>
[Tweak condition as suggested by Sean. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index bcffae2..1a70e11 100644 (file)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -259,7 +259,7 @@ u32 svm_msrpm_offset(u32 msr)
 static int get_max_npt_level(void)
 {
 #ifdef CONFIG_X86_64
-       return PT64_ROOT_4LEVEL;
+       return pgtable_l5_enabled() ? PT64_ROOT_5LEVEL : PT64_ROOT_4LEVEL;
 #else
        return PT32E_ROOT_LEVEL;
 #endif
@@ -460,11 +460,6 @@ 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;
 }