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

mainline inclusion
from mainline-v5.15
commit 43e540cc
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5NGRU
CVE: NA

-------------------------------------------------

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

arch/x86/kvm/svm/svm.c

@@ -257,7 +257,7 @@ static inline void invlpga(unsigned long addr, u32 asid)
 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
@@ -443,11 +443,6 @@ 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;
 }