From f2a55d08d7e1a5746dad80fc5eda023eff2eeea5 Mon Sep 17 00:00:00 2001 From: Saurabh Sengar Date: Tue, 19 Sep 2023 21:04:35 -0700 Subject: x86/hyperv: Restrict get_vtl to only VTL platforms When Linux runs in a non-default VTL (CONFIG_HYPERV_VTL_MODE=y), get_vtl() must never fail as its return value is used in negotiations with the host. In the more generic case, (CONFIG_HYPERV_VTL_MODE=n) the VTL is always zero so there's no need to do the hypercall. Make get_vtl() BUG() in case of failure and put the implementation under "if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)" to avoid the call altogether in the most generic use case. Signed-off-by: Saurabh Sengar Reviewed-by: Vitaly Kuznetsov Signed-off-by: Wei Liu Link: https://lore.kernel.org/r/1695182675-13405-1-git-send-email-ssengar@linux.microsoft.com --- arch/x86/hyperv/hv_init.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'arch/x86/hyperv') diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 783ed339f341..f0128fd4031d 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -394,6 +394,7 @@ static void __init hv_get_partition_id(void) local_irq_restore(flags); } +#if IS_ENABLED(CONFIG_HYPERV_VTL_MODE) static u8 __init get_vtl(void) { u64 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_REGISTERS; @@ -416,13 +417,16 @@ static u8 __init get_vtl(void) if (hv_result_success(ret)) { ret = output->as64.low & HV_X64_VTL_MASK; } else { - pr_err("Failed to get VTL(%lld) and set VTL to zero by default.\n", ret); - ret = 0; + pr_err("Failed to get VTL(error: %lld) exiting...\n", ret); + BUG(); } local_irq_restore(flags); return ret; } +#else +static inline u8 get_vtl(void) { return 0; } +#endif /* * This function is to be invoked early in the boot sequence after the @@ -604,8 +608,7 @@ skip_hypercall_pg_init: hv_query_ext_cap(0); /* Find the VTL */ - if (!ms_hyperv.paravisor_present && hv_isolation_type_snp()) - ms_hyperv.vtl = get_vtl(); + ms_hyperv.vtl = get_vtl(); return; -- cgit v1.2.3