Secure AVIC hardware provides APIC backing page
to aid the guest in limiting which interrupt
vectors can be injected into the guest. Hyper-V
introduces a new register HV_X64_REGISTER_SEV_GPA_PAGE
to notify hypervisor with APIC backing page and call
it in Secure AVIC driver.

Setting APIC backing page for APs takes place before
allocating hyperv_pcpu_input_arg and so allocate
hv_vp_early_input_arg to handle such case.

Signed-off-by: Roman Kisel <[email protected]>
Signed-off-by: Tianyu Lan <[email protected]>
---
 arch/x86/hyperv/hv_init.c           | 24 +++++++++++++++++-
 arch/x86/hyperv/ivm.c               | 38 ++++++++++++++++++++++++++++
 arch/x86/include/asm/mshyperv.h     |  2 ++
 arch/x86/kernel/apic/x2apic_savic.c |  9 ++++++-
 include/hyperv/hvgdk_mini.h         | 39 +++++++++++++++++++++++++++++
 5 files changed, 110 insertions(+), 2 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index a38bb96c9f5e..3fa8e91cd03f 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -39,6 +39,7 @@
 void *hv_hypercall_pg;
 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
 
+void *hv_vp_early_input_arg;
 union hv_ghcb * __percpu *hv_ghcb_pg;
 
 /* Storage to save the hypercall page temporarily for hibernation */
@@ -412,6 +413,7 @@ void __init hyperv_init(void)
        u64 guest_id;
        union hv_x64_msr_hypercall_contents hypercall_msr;
        int cpuhp;
+       int ret;
 
        if (x86_hyper_type != X86_HYPER_MS_HYPERV)
                return;
@@ -419,6 +421,22 @@ void __init hyperv_init(void)
        if (hv_common_init())
                return;
 
+       if (cc_platform_has(CC_ATTR_SNP_SECURE_AVIC)) {
+               hv_vp_early_input_arg = kcalloc(num_possible_cpus(),
+                                            PAGE_SIZE,
+                                            GFP_KERNEL);
+               if (hv_vp_early_input_arg) {
+                       ret = set_memory_decrypted((u64)hv_vp_early_input_arg,
+                                            num_possible_cpus());
+                       if (ret) {
+                               kfree(hv_vp_early_input_arg);
+                               goto common_free;
+                       }
+               } else {
+                       goto common_free;
+               }
+       }
+
        /*
         * 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.
@@ -433,7 +451,7 @@ void __init hyperv_init(void)
                ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
 
                if (!hv_isolation_type_tdx())
-                       goto common_free;
+                       goto free_vp_early_input_arg;
        }
 
        if (ms_hyperv.paravisor_present && hv_isolation_type_snp()) {
@@ -591,6 +609,10 @@ void __init hyperv_init(void)
 free_vp_assist_page:
        kfree(hv_vp_assist_page);
        hv_vp_assist_page = NULL;
+free_vp_early_input_arg:
+       set_memory_encrypted((u64)hv_vp_early_input_arg, num_possible_cpus());
+       kfree(hv_vp_early_input_arg);
+       hv_vp_early_input_arg = NULL;
 common_free:
        hv_common_free();
 }
diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index ade6c665c97e..e69dae57730c 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -291,6 +291,44 @@ static void snp_cleanup_vmsa(struct sev_es_save_area *vmsa)
                free_page((unsigned long)vmsa);
 }
 
+enum es_result hv_set_savic_backing_page(u64 gfn)
+{
+       u64 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_SET_VP_REGISTERS;
+       struct hv_set_vp_registers_input *input
+               = hv_vp_early_input_arg + smp_processor_id() * PAGE_SIZE;
+       union hv_x64_register_sev_gpa_page value;
+       unsigned long flags;
+       int retry = 5;
+       u64 ret;
+
+       local_irq_save(flags);
+
+       value.enabled = 1;
+       value.reserved = 0;
+       value.pagenumber = gfn;
+
+       memset(input, 0, struct_size(input, element, 1));
+       input->header.partitionid = HV_PARTITION_ID_SELF;
+       input->header.vpindex = HV_VP_INDEX_SELF;
+       input->header.inputvtl = ms_hyperv.vtl;
+       input->element[0].name = HV_X64_REGISTER_SEV_AVIC_GPA;
+       input->element[0].value.reg64 = value.u64;
+
+       do {
+               ret = hv_do_hypercall(control, input, NULL);
+       } while (ret == HV_STATUS_TIME_OUT && retry--);
+
+       if (!hv_result_success(ret))
+               pr_err("Failed to set Secure AVIC backing page %llx.\n", ret);
+
+       local_irq_restore(flags);
+
+       if (hv_result_success(ret))
+               return ES_OK;
+       else
+               return ES_VMM_ERROR;
+}
+
 int hv_snp_boot_ap(u32 apic_id, unsigned long start_ip, unsigned int cpu)
 {
        struct sev_es_save_area *vmsa = (struct sev_es_save_area *)
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index abc4659f5809..b140558816de 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -43,6 +43,7 @@ static inline unsigned char hv_get_nmi_reason(void)
 extern bool hyperv_paravisor_present;
 
 extern void *hv_hypercall_pg;
+extern void *hv_vp_early_input_arg;
 
 extern union hv_ghcb * __percpu *hv_ghcb_pg;
 
@@ -252,6 +253,7 @@ int hv_unmap_ioapic_interrupt(int ioapic_id, struct 
hv_interrupt_entry *entry);
 bool hv_ghcb_negotiate_protocol(void);
 void __noreturn hv_ghcb_terminate(unsigned int set, unsigned int reason);
 int hv_snp_boot_ap(u32 apic_id, unsigned long start_ip, unsigned int cpu);
+enum es_result hv_set_savic_backing_page(u64 gfn);
 #else
 static inline bool hv_ghcb_negotiate_protocol(void) { return false; }
 static inline void hv_ghcb_terminate(unsigned int set, unsigned int reason) {}
diff --git a/arch/x86/kernel/apic/x2apic_savic.c 
b/arch/x86/kernel/apic/x2apic_savic.c
index dbc5678bc3b6..60bdb524de53 100644
--- a/arch/x86/kernel/apic/x2apic_savic.c
+++ b/arch/x86/kernel/apic/x2apic_savic.c
@@ -14,6 +14,7 @@
 
 #include <asm/apic.h>
 #include <asm/sev.h>
+#include <asm/mshyperv.h>
 
 #include "local.h"
 
@@ -342,6 +343,7 @@ static void savic_setup(void)
        void *ap = this_cpu_ptr(savic_page);
        enum es_result res;
        unsigned long gpa;
+       unsigned long gfn;
 
        /*
         * Before Secure AVIC is enabled, APIC MSR reads are intercepted.
@@ -350,6 +352,7 @@ static void savic_setup(void)
        apic_set_reg(ap, APIC_ID, native_apic_msr_read(APIC_ID));
 
        gpa = __pa(ap);
+       gfn = gpa >> PAGE_SHIFT;
 
        /*
         * The NPT entry for a vCPU's APIC backing page must always be
@@ -361,7 +364,11 @@ static void savic_setup(void)
         * VMRUN, the hypervisor makes use of this information to make sure
         * the APIC backing page is mapped in NPT.
         */
-       res = savic_register_gpa(gpa);
+       if (hv_isolation_type_snp())
+               res = hv_set_savic_backing_page(gfn);
+       else
+               res = savic_register_gpa(gpa);
+
        if (res != ES_OK)
                sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SAVIC_FAIL);
 
diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
index 1be7f6a02304..e3092469aafe 100644
--- a/include/hyperv/hvgdk_mini.h
+++ b/include/hyperv/hvgdk_mini.h
@@ -1170,6 +1170,28 @@ union hv_register_value {
        union hv_arm64_pending_synthetic_exception_event 
pending_synthetic_exception_event;
 };
 
+/* HvSetVpRegisters hypercall with variable size reg name/value list*/
+struct hv_set_vp_registers_input {
+       struct {
+               u64 partitionid;
+               u32 vpindex;
+               u8  inputvtl;
+               u8  padding[3];
+       } header;
+       struct {
+               u32 name;
+               u32 padding1;
+               u64 padding2;
+               union {
+                       union hv_register_value value;
+                       struct {
+                               u64 valuelow;
+                               u64 valuehigh;
+                       };
+               };
+       } element[];
+} __packed;
+
 /* NOTE: Linux helper struct - NOT from Hyper-V code. */
 struct hv_output_get_vp_registers {
        DECLARE_FLEX_ARRAY(union hv_register_value, values);
@@ -1210,6 +1232,15 @@ struct hv_input_get_vp_registers {
        u32 names[];
 } __packed;
 
+union hv_x64_register_sev_gpa_page {
+       u64 u64;
+       struct {
+               u64 enabled:1;
+               u64 reserved:11;
+               u64 pagenumber:52;
+       };
+} __packed;
+
 struct hv_input_set_vp_registers {
        u64 partition_id;
        u32 vp_index;
@@ -1230,6 +1261,14 @@ struct hv_send_ipi {      /* 
HV_INPUT_SEND_SYNTHETIC_CLUSTER_IPI */
 
 #define        HV_VTL_MASK                     GENMASK(3, 0)
 
+/*
+ * Registers are only accessible via HVCALL_GET_VP_REGISTERS hvcall and
+ * there is not associated MSR address.
+ */
+#define        HV_X64_REGISTER_VSM_VP_STATUS   0x000D0003
+#define        HV_X64_VTL_MASK                 GENMASK(3, 0)
+#define        HV_X64_REGISTER_SEV_AVIC_GPA    0x00090043
+
 /* Hyper-V memory host visibility */
 enum hv_mem_host_visibility {
        VMBUS_PAGE_NOT_VISIBLE          = 0,
-- 
2.25.1


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