Commit 68f2f2bc authored by Dexuan Cui's avatar Dexuan Cui Committed by Wei Liu
Browse files

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: default avatarMichael Kelley <mikelley@microsoft.com>
Signed-off-by: default avatarDexuan Cui <decui@microsoft.com>
Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
Link: https://lore.kernel.org/r/20230824080712.30327-4-decui@microsoft.com
parent d6e0228d

arch/x86/hyperv/hv_apic.c

+12 −3
Original line number Diff line number Diff line
@@ -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)

	/* 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;
@@ -231,8 +234,14 @@ 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;

arch/x86/hyperv/hv_init.c

+15 −4
Original line number Diff line number Diff line
@@ -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
@@ -442,10 +443,20 @@ void __init hyperv_init(void) 
	if (hv_common_init())

		return;



	/*

	 * 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);

					    sizeof(*hv_vp_assist_page),

					    GFP_KERNEL);

	if (!hv_vp_assist_page) {

		ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;



		if (!hv_isolation_type_tdx())

			goto common_free;

	}

arch/x86/kernel/cpu/mshyperv.c

+14 −0
Original line number Diff line number Diff line
@@ -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;

			}

		}

	}

drivers/hv/hv.c

+7 −2
Original line number Diff line number Diff line
@@ -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);