[RFC PATCH V4 10/17] x86/hyperv: Add smp support for sev-snp guest

From: Tianyu Lan
Date: Mon Apr 03 2023 - 13:45:02 EST

From: Tianyu Lan <tiala@xxxxxxxxxxxxx>

The wakeup_secondary_cpu callback was populated with wakeup_
cpu_via_vmgexit() which doesn't work for Hyper-V and Hyper-V
requires to call Hyper-V specific hvcall to start APs. So override
it with Hyper-V specific hook to start AP sev_es_save_area data
structure.

Signed-off-by: Tianyu Lan <tiala@xxxxxxxxxxxxx>
---
Change sicne RFC v3:
* Replace struct sev_es_save_area with struct
vmcb_save_area
* Move code from mshyperv.c to ivm.c

Change since RFC v2:
* Add helper function to initialize segment
* Fix some coding style
---
arch/x86/hyperv/ivm.c | 89 +++++++++++++++++++++++++++++++
arch/x86/include/asm/mshyperv.h | 18 +++++++
arch/x86/include/asm/sev.h | 13 +++++
arch/x86/include/asm/svm.h | 15 +++++-
arch/x86/kernel/cpu/mshyperv.c | 13 ++++-
arch/x86/kernel/sev.c | 4 +-
include/asm-generic/hyperv-tlfs.h | 19 +++++++
7 files changed, 166 insertions(+), 5 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index c0f3fa924163..51243148b8e6 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -22,11 +22,15 @@
#include <asm/sev.h>
#include <asm/realmode.h>
#include <asm/e820/api.h>
+#include <asm/desc.h>

#ifdef CONFIG_AMD_MEM_ENCRYPT

#define GHCB_USAGE_HYPERV_CALL 1

+static u8 ap_start_input_arg[PAGE_SIZE] __bss_decrypted __aligned(PAGE_SIZE);
+static u8 ap_start_stack[PAGE_SIZE] __aligned(PAGE_SIZE);
+
union hv_ghcb {
struct ghcb ghcb;
struct {
@@ -437,6 +441,91 @@ __init void hv_sev_init_mem_and_cpu(void)
}
}

+#define hv_populate_vmcb_seg(seg, gdtr_base) \
+do { \
+ if (seg.selector) { \
+ seg.base = 0; \
+ seg.limit = HV_AP_SEGMENT_LIMIT; \
+ seg.attrib = *(u16 *)(gdtr_base + seg.selector + 5); \
+ seg.attrib = (seg.attrib & 0xFF) | ((seg.attrib >> 4) & 0xF00); \
+ } \
+} while (0) \
+
+int hv_snp_boot_ap(int cpu, unsigned long start_ip)
+{
+ struct sev_es_save_area *vmsa = (struct sev_es_save_area *)
+ __get_free_page(GFP_KERNEL | __GFP_ZERO);
+ struct desc_ptr gdtr;
+ u64 ret, retry = 5;
+ struct hv_start_virtual_processor_input *start_vp_input;
+ union sev_rmp_adjust rmp_adjust;
+ unsigned long flags;
+
+ native_store_gdt(&gdtr);
+
+ vmsa->gdtr.base = gdtr.address;
+ vmsa->gdtr.limit = gdtr.size;
+
+ asm volatile("movl %%es, %%eax;" : "=a" (vmsa->es.selector));
+ hv_populate_vmcb_seg(vmsa->es, vmsa->gdtr.base);
+
+ asm volatile("movl %%cs, %%eax;" : "=a" (vmsa->cs.selector));
+ hv_populate_vmcb_seg(vmsa->cs, vmsa->gdtr.base);
+
+ asm volatile("movl %%ss, %%eax;" : "=a" (vmsa->ss.selector));
+ hv_populate_vmcb_seg(vmsa->ss, vmsa->gdtr.base);
+
+ asm volatile("movl %%ds, %%eax;" : "=a" (vmsa->ds.selector));
+ hv_populate_vmcb_seg(vmsa->ds, vmsa->gdtr.base);
+
+ vmsa->efer = native_read_msr(MSR_EFER);
+
+ asm volatile("movq %%cr4, %%rax;" : "=a" (vmsa->cr4));
+ asm volatile("movq %%cr3, %%rax;" : "=a" (vmsa->cr3));
+ asm volatile("movq %%cr0, %%rax;" : "=a" (vmsa->cr0));
+
+ vmsa->xcr0 = 1;
+ vmsa->g_pat = HV_AP_INIT_GPAT_DEFAULT;
+ vmsa->rip = (u64)secondary_startup_64_no_verify;
+ vmsa->rsp = (u64)&ap_start_stack[PAGE_SIZE];
+
+ vmsa->sev_features.snp = 1;
+ vmsa->sev_features.restrict_injection = 1;
+
+ rmp_adjust.as_uint64 = 0;
+ rmp_adjust.target_vmpl = 1;
+ rmp_adjust.vmsa = 1;
+ ret = rmpadjust((unsigned long)vmsa, RMP_PG_SIZE_4K,
+ rmp_adjust.as_uint64);
+ if (ret != 0) {
+ pr_err("RMPADJUST(%llx) failed: %llx\n", (u64)vmsa, ret);
+ return ret;
+ }
+
+ local_irq_save(flags);
+ start_vp_input =
+ (struct hv_start_virtual_processor_input *)ap_start_input_arg;
+ memset(start_vp_input, 0, sizeof(*start_vp_input));
+ start_vp_input->partitionid = -1;
+ start_vp_input->vpindex = cpu;
+ start_vp_input->targetvtl = ms_hyperv.vtl;
+ *(u64 *)&start_vp_input->context[0] = __pa(vmsa) | 1;
+
+ do {
+ ret = hv_do_hypercall(HVCALL_START_VIRTUAL_PROCESSOR,
+ start_vp_input, NULL);
+ } while (hv_result(ret) == HV_STATUS_TIME_OUT && retry--);
+
+ if (!hv_result_success(ret)) {
+ pr_err("HvCallStartVirtualProcessor failed: %llx\n", ret);
+ goto done;
+ }
+
+done:
+ local_irq_restore(flags);
+ return ret;
+}
+
void __init hv_vtom_init(void)
{
/*
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index a4a59007b5f2..e23c987deb7a 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -55,6 +55,20 @@ struct memory_map_entry {
u32 reserved;
};

+/*
+ * DEFAULT INIT GPAT and SEGMENT LIMIT value in struct VMSA
+ * to start AP in enlightened SEV guest.
+ */
+#define HV_AP_INIT_GPAT_DEFAULT 0x0007040600070406ULL
+#define HV_AP_SEGMENT_LIMIT 0xffffffff
+
+/*
+ * DEFAULT INIT GPAT and SEGMENT LIMIT value in struct VMSA
+ * to start AP in enlightened SEV guest.
+ */
+#define HV_AP_INIT_GPAT_DEFAULT 0x0007040600070406ULL
+#define HV_AP_SEGMENT_LIMIT 0xffffffff
+
int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages);
int hv_call_add_logical_proc(int node, u32 lp_index, u32 acpi_id);
int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32 flags);
@@ -253,6 +267,8 @@ struct irq_domain *hv_create_pci_msi_domain(void);
int hv_map_ioapic_interrupt(int ioapic_id, bool level, int vcpu, int vector,
struct hv_interrupt_entry *entry);
int hv_unmap_ioapic_interrupt(int ioapic_id, struct hv_interrupt_entry *entry);
+int hv_set_mem_host_visibility(unsigned long addr, int numpages, bool visible);
+int hv_snp_boot_ap(int cpu, unsigned long start_ip);

#ifdef CONFIG_AMD_MEM_ENCRYPT
void hv_ghcb_msr_write(u64 msr, u64 value);
@@ -261,6 +277,7 @@ bool hv_ghcb_negotiate_protocol(void);
void hv_ghcb_terminate(unsigned int set, unsigned int reason);
void hv_vtom_init(void);
void hv_sev_init_mem_and_cpu(void);
+int hv_snp_boot_ap(int cpu, unsigned long start_ip);
#else
static inline void hv_ghcb_msr_write(u64 msr, u64 value) {}
static inline void hv_ghcb_msr_read(u64 msr, u64 *value) {}
@@ -268,6 +285,7 @@ static inline bool hv_ghcb_negotiate_protocol(void) { return false; }
static inline void hv_ghcb_terminate(unsigned int set, unsigned int reason) {}
static inline void hv_vtom_init(void) {}
static inline void hv_sev_init_mem_and_cpu(void) {}
+static int hv_snp_boot_ap(int cpu, unsigned long start_ip) {}
#endif

extern bool hv_isolation_type_snp(void);
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index ebc271bb6d8e..e34aaf730220 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -86,6 +86,19 @@ extern bool handle_vc_boot_ghcb(struct pt_regs *regs);

#define RMPADJUST_VMSA_PAGE_BIT BIT(16)

+union sev_rmp_adjust {
+ u64 as_uint64;
+ struct {
+ unsigned long target_vmpl : 8;
+ unsigned long enable_read : 1;
+ unsigned long enable_write : 1;
+ unsigned long enable_user_execute : 1;
+ unsigned long enable_kernel_execute : 1;
+ unsigned long reserved1 : 4;
+ unsigned long vmsa : 1;
+ };
+};
+
/* SNP Guest message request */
struct snp_req_data {
unsigned long req_gpa;
diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index cb1ee53ad3b1..bcf970901512 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -423,7 +423,20 @@ struct sev_es_save_area {
u64 guest_exit_info_2;
u64 guest_exit_int_info;
u64 guest_nrip;
- u64 sev_features;
+ union {
+ struct {
+ u64 snp : 1;
+ u64 vtom : 1;
+ u64 reflectvc : 1;
+ u64 restrict_injection : 1;
+ u64 alternate_injection : 1;
+ u64 full_debug : 1;
+ u64 reserved1 : 1;
+ u64 snpbtb_isolation : 1;
+ u64 resrved2 : 56;
+ };
+ u64 val;
+ } sev_features;
u64 vintr_ctrl;
u64 guest_exit_code;
u64 virtual_tom;
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 71820bbf9e90..829234ba8da5 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -300,6 +300,16 @@ static void __init hv_smp_prepare_cpus(unsigned int max_cpus)

native_smp_prepare_cpus(max_cpus);

+ /*
+ * Override wakeup_secondary_cpu callback for SEV-SNP
+ * enlightened guest.
+ */
+ if (hv_isolation_type_en_snp())
+ apic->wakeup_secondary_cpu = hv_snp_boot_ap;
+
+ if (!hv_root_partition)
+ return;
+
#ifdef CONFIG_X86_64
for_each_present_cpu(i) {
if (i == 0)
@@ -503,8 +513,7 @@ static void __init ms_hyperv_init_platform(void)

# ifdef CONFIG_SMP
smp_ops.smp_prepare_boot_cpu = hv_smp_prepare_boot_cpu;
- if (hv_root_partition)
- smp_ops.smp_prepare_cpus = hv_smp_prepare_cpus;
+ smp_ops.smp_prepare_cpus = hv_smp_prepare_cpus;
# endif

/*
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 679026a640ef..b3f95fcb8b18 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -1080,7 +1080,7 @@ static int wakeup_cpu_via_vmgexit(int apic_id, unsigned long start_ip)
* SEV_FEATURES (matches the SEV STATUS MSR right shifted 2 bits)
*/
vmsa->vmpl = 0;
- vmsa->sev_features = sev_status >> 2;
+ vmsa->sev_features.val = sev_status >> 2;

/* Switch the page over to a VMSA page now that it is initialized */
ret = snp_set_vmsa(vmsa, true);
@@ -1097,7 +1097,7 @@ static int wakeup_cpu_via_vmgexit(int apic_id, unsigned long start_ip)
ghcb = __sev_get_ghcb(&state);

vc_ghcb_invalidate(ghcb);
- ghcb_set_rax(ghcb, vmsa->sev_features);
+ ghcb_set_rax(ghcb, vmsa->sev_features.val);
ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_CREATION);
ghcb_set_sw_exit_info_1(ghcb, ((u64)apic_id << 32) | SVM_VMGEXIT_AP_CREATE);
ghcb_set_sw_exit_info_2(ghcb, __pa(vmsa));
diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index ea406e901469..b2f14aa608f7 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h
@@ -148,6 +148,7 @@ union hv_reference_tsc_msr {
#define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST 0x0003
#define HVCALL_NOTIFY_LONG_SPIN_WAIT 0x0008
#define HVCALL_SEND_IPI 0x000b
+#define HVCALL_ENABLE_VP_VTL 0x000f
#define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX 0x0013
#define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX 0x0014
#define HVCALL_SEND_IPI_EX 0x0015
@@ -165,6 +166,7 @@ union hv_reference_tsc_msr {
#define HVCALL_MAP_DEVICE_INTERRUPT 0x007c
#define HVCALL_UNMAP_DEVICE_INTERRUPT 0x007d
#define HVCALL_RETARGET_INTERRUPT 0x007e
+#define HVCALL_START_VIRTUAL_PROCESSOR 0x0099
#define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_SPACE 0x00af
#define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_LIST 0x00b0
#define HVCALL_MODIFY_SPARSE_GPA_PAGE_HOST_VISIBILITY 0x00db
@@ -220,6 +222,7 @@ enum HV_GENERIC_SET_FORMAT {
#define HV_STATUS_INVALID_PORT_ID 17
#define HV_STATUS_INVALID_CONNECTION_ID 18
#define HV_STATUS_INSUFFICIENT_BUFFERS 19
+#define HV_STATUS_TIME_OUT 0x78

/*
* The Hyper-V TimeRefCount register and the TSC
@@ -779,6 +782,22 @@ struct hv_input_unmap_device_interrupt {
struct hv_interrupt_entry interrupt_entry;
} __packed;

+struct hv_enable_vp_vtl_input {
+ u64 partitionid;
+ u32 vpindex;
+ u8 targetvtl;
+ u8 padding[3];
+ u8 context[0xe0];
+} __packed;
+
+struct hv_start_virtual_processor_input {
+ u64 partitionid;
+ u32 vpindex;
+ u8 targetvtl;
+ u8 padding[3];
+ u8 context[0xe0];
+} __packed;
+
#define HV_SOURCE_SHADOW_NONE 0x0
#define HV_SOURCE_SHADOW_BRIDGE_BUS_RANGE 0x1

--
2.25.1