From: Dexuan Cui Date: Thu, 24 Aug 2023 08:07:05 +0000 (-0700) Subject: Drivers: hv: vmbus: Support fully enlightened TDX guests X-Git-Tag: v6.6-rc1~69^2~8 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=68f2f2bc163d4427b04f0fb6421f091f948175fe;p=linux-2.6-block.git Drivers: hv: vmbus: Support fully enlightened TDX guests Add Hyper-V specific code so that a fully enlightened TDX guest (i.e. without the paravisor) can run on Hyper-V: Don't use hv_vp_assist_page. Use GHCI instead. Don't try to use the unsupported HV_REGISTER_CRASH_CTL. Don't trust (use) Hyper-V's TLB-flushing hypercalls. Don't use lazy EOI. Share the SynIC Event/Message pages with the hypervisor. Don't use the Hyper-V TSC page for now, because non-trivial work is required to share the page with the hypervisor. Reviewed-by: Michael Kelley Signed-off-by: Dexuan Cui Signed-off-by: Wei Liu Link: https://lore.kernel.org/r/20230824080712.30327-4-decui@microsoft.com --- diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c index 1fbda2f94184..cb7429046d18 100644 --- a/arch/x86/hyperv/hv_apic.c +++ b/arch/x86/hyperv/hv_apic.c @@ -177,8 +177,11 @@ static bool __send_ipi_mask(const struct cpumask *mask, int vector, (exclude_self && weight == 1 && cpumask_test_cpu(this_cpu, mask))) return true; - if (!hv_hypercall_pg) - return false; + /* A fully enlightened TDX VM uses GHCI rather than hv_hypercall_pg. */ + if (!hv_hypercall_pg) { + if (ms_hyperv.paravisor_present || !hv_isolation_type_tdx()) + return false; + } if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR)) return false; @@ -231,9 +234,15 @@ static bool __send_ipi_one(int cpu, int vector) trace_hyperv_send_ipi_one(cpu, vector); - if (!hv_hypercall_pg || (vp == VP_INVAL)) + if (vp == VP_INVAL) return false; + /* A fully enlightened TDX VM uses GHCI rather than hv_hypercall_pg. */ + if (!hv_hypercall_pg) { + if (ms_hyperv.paravisor_present || !hv_isolation_type_tdx()) + return false; + } + if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR)) return false; diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 255e02ec467e..c1c1b4e1502f 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -80,7 +80,7 @@ static int hyperv_init_ghcb(void) static int hv_cpu_init(unsigned int cpu) { union hv_vp_assist_msr_contents msr = { 0 }; - struct hv_vp_assist_page **hvp = &hv_vp_assist_page[cpu]; + struct hv_vp_assist_page **hvp; int ret; ret = hv_common_cpu_init(cpu); @@ -90,6 +90,7 @@ static int hv_cpu_init(unsigned int cpu) if (!hv_vp_assist_page) return 0; + hvp = &hv_vp_assist_page[cpu]; if (hv_root_partition) { /* * For root partition we get the hypervisor provided VP assist @@ -442,11 +443,21 @@ void __init hyperv_init(void) if (hv_common_init()) return; - hv_vp_assist_page = kcalloc(num_possible_cpus(), - sizeof(*hv_vp_assist_page), GFP_KERNEL); + /* + * The VP assist page is useless to a TDX guest: the only use we + * would have for it is lazy EOI, which can not be used with TDX. + */ + if (hv_isolation_type_tdx()) + hv_vp_assist_page = NULL; + else + hv_vp_assist_page = kcalloc(num_possible_cpus(), + sizeof(*hv_vp_assist_page), + GFP_KERNEL); if (!hv_vp_assist_page) { ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED; - goto common_free; + + if (!hv_isolation_type_tdx()) + goto common_free; } if (hv_isolation_type_snp()) { diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index 63093870ec33..ff3d9c5de19c 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -420,6 +420,20 @@ static void __init ms_hyperv_init_platform(void) static_branch_enable(&isolation_type_en_snp); } else if (hv_get_isolation_type() == HV_ISOLATION_TYPE_TDX) { static_branch_enable(&isolation_type_tdx); + + /* A TDX VM must use x2APIC and doesn't use lazy EOI. */ + ms_hyperv.hints &= ~HV_X64_APIC_ACCESS_RECOMMENDED; + + if (!ms_hyperv.paravisor_present) { + /* To be supported: more work is required. */ + ms_hyperv.features &= ~HV_MSR_REFERENCE_TSC_AVAILABLE; + + /* HV_REGISTER_CRASH_CTL is unsupported. */ + ms_hyperv.misc_features &= ~HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE; + + /* Don't trust Hyper-V's TLB-flushing hypercalls. */ + ms_hyperv.hints &= ~HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED; + } } } diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c index ec6e35a0d9bf..d1064118a72f 100644 --- a/drivers/hv/hv.c +++ b/drivers/hv/hv.c @@ -121,11 +121,15 @@ int hv_synic_alloc(void) (void *)get_zeroed_page(GFP_ATOMIC); if (hv_cpu->synic_event_page == NULL) { pr_err("Unable to allocate SYNIC event page\n"); + + free_page((unsigned long)hv_cpu->synic_message_page); + hv_cpu->synic_message_page = NULL; goto err; } } - if (hv_isolation_type_en_snp()) { + if (!ms_hyperv.paravisor_present && + (hv_isolation_type_en_snp() || hv_isolation_type_tdx())) { ret = set_memory_decrypted((unsigned long) hv_cpu->synic_message_page, 1); if (ret) { @@ -174,7 +178,8 @@ void hv_synic_free(void) = per_cpu_ptr(hv_context.cpu_context, cpu); /* It's better to leak the page if the encryption fails. */ - if (hv_isolation_type_en_snp()) { + if (!ms_hyperv.paravisor_present && + (hv_isolation_type_en_snp() || hv_isolation_type_tdx())) { if (hv_cpu->synic_message_page) { ret = set_memory_encrypted((unsigned long) hv_cpu->synic_message_page, 1);