When CONFIG_HYPERV is not set, arch/x86/hyperv/ivm.c is not built (see arch/x86/Kbuild), so 'isolation_type_en_snp' in the ivm.c is not defined, and this failure happens: ld: arch/x86/kernel/cpu/mshyperv.o: in function `ms_hyperv_init_platform': arch/x86/kernel/cpu/mshyperv.c:417: undefined reference to `isolation_type_en_snp' Fix the failure by testing hv_get_isolation_type() and ms_hyperv.paravisor_present for a fully enlightened SNP VM: when CONFIG_HYPERV is not set, hv_get_isolation_type() is defined as a static inline function that always returns HV_ISOLATION_TYPE_NONE (see include/asm-generic/mshyperv.h), so the compiler won't generate any code for the ms_hyperv.paravisor_present and static_branch_enable(). Reported-by: Tom Lendacky <thomas.lendacky@xxxxxxx> Closes: https://lore.kernel.org/lkml/b4979997-23b9-0c43-574e-e4a3506500ff@xxxxxxx/ Fixes: d6e2d6524437 ("x86/hyperv: Add sev-snp enlightened guest static key") Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx> --- arch/x86/kernel/cpu/mshyperv.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index 26b9fcabd7d95..c8d3ca2b0e0ee 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -413,10 +413,11 @@ static void __init ms_hyperv_init_platform(void) ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b); - if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) { - static_branch_enable(&isolation_type_en_snp); - } else if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) { - static_branch_enable(&isolation_type_snp); + if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) { + if (ms_hyperv.paravisor_present) + static_branch_enable(&isolation_type_snp); + else + static_branch_enable(&isolation_type_en_snp); } } -- 2.25.1
