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x86/hyperv: Add smp support for SEV-SNP guest 

In the AMD SEV-SNP guest, AP needs to be started up via sev es
save area and Hyper-V requires to call HVCALL_START_VP hypercall
to pass the gpa of sev es save area with AP's vp index and VTL(Virtual
trust level) parameters. Override wakeup_secondary_cpu_64 callback
with hv_snp_boot_ap.

Reviewed-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Tianyu Lan <tiala@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Link: https://lore.kernel.org/r/20230818102919.1318039-8-ltykernel@gmail.com
This commit is contained in:
Tianyu Lan 2023-08-18 06:29:17 -04:00 committed by Wei Liu
parent 45f46b1ac9
commit 44676bb9d5
4 changed files with 157 additions and 1 deletions
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138
arch/x86/hyperv/ivm.c
View File

@ -18,11 +18,20 @@
#include <asm/mshyperv.h>
#include <asm/hypervisor.h>
#include <asm/mtrr.h>
#include <asm/coco.h>
#include <asm/io_apic.h>
#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 {
@ -56,6 +65,8 @@ union hv_ghcb {
} hypercall;
} __packed __aligned(HV_HYP_PAGE_SIZE);
static DEFINE_PER_CPU(struct sev_es_save_area *, hv_sev_vmsa);
static u16 hv_ghcb_version __ro_after_init;
u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size)
@ -357,6 +368,133 @@ static bool hv_is_private_mmio(u64 addr)
return false;
}
#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) \
static int snp_set_vmsa(void *va, bool vmsa)
{
u64 attrs;
/*
* Running at VMPL0 allows the kernel to change the VMSA bit for a page
* using the RMPADJUST instruction. However, for the instruction to
* succeed it must target the permissions of a lesser privileged
* (higher numbered) VMPL level, so use VMPL1 (refer to the RMPADJUST
* instruction in the AMD64 APM Volume 3).
*/
attrs = 1;
if (vmsa)
attrs |= RMPADJUST_VMSA_PAGE_BIT;
return rmpadjust((unsigned long)va, RMP_PG_SIZE_4K, attrs);
}
static void snp_cleanup_vmsa(struct sev_es_save_area *vmsa)
{
int err;
err = snp_set_vmsa(vmsa, false);
if (err)
pr_err("clear VMSA page failed (%u), leaking page\n", err);
else
free_page((unsigned long)vmsa);
}
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 sev_es_save_area *cur_vmsa;
struct desc_ptr gdtr;
u64 ret, retry = 5;
struct hv_enable_vp_vtl *start_vp_input;
unsigned long flags;
if (!vmsa)
return -ENOMEM;
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];
/*
* Set the SNP-specific fields for this VMSA:
* VMPL level
* SEV_FEATURES (matches the SEV STATUS MSR right shifted 2 bits)
*/
vmsa->vmpl = 0;
vmsa->sev_features = sev_status >> 2;
ret = snp_set_vmsa(vmsa, true);
if (!ret) {
pr_err("RMPADJUST(%llx) failed: %llx\n", (u64)vmsa, ret);
free_page((u64)vmsa);
return ret;
}
local_irq_save(flags);
start_vp_input = (struct hv_enable_vp_vtl *)ap_start_input_arg;
memset(start_vp_input, 0, sizeof(*start_vp_input));
start_vp_input->partition_id = -1;
start_vp_input->vp_index = cpu;
start_vp_input->target_vtl.target_vtl = ms_hyperv.vtl;
*(u64 *)&start_vp_input->vp_context = __pa(vmsa) | 1;
do {
ret = hv_do_hypercall(HVCALL_START_VP,
start_vp_input, NULL);
} while (hv_result(ret) == HV_STATUS_TIME_OUT && retry--);
local_irq_restore(flags);
if (!hv_result_success(ret)) {
pr_err("HvCallStartVirtualProcessor failed: %llx\n", ret);
snp_cleanup_vmsa(vmsa);
vmsa = NULL;
}
cur_vmsa = per_cpu(hv_sev_vmsa, cpu);
/* Free up any previous VMSA page */
if (cur_vmsa)
snp_cleanup_vmsa(cur_vmsa);
/* Record the current VMSA page */
per_cpu(hv_sev_vmsa, cpu) = vmsa;
return ret;
}
void __init hv_vtom_init(void)
{
/*

8
arch/x86/include/asm/mshyperv.h
View File

@ -49,6 +49,12 @@ extern u64 hv_current_partition_id;
extern union hv_ghcb * __percpu *hv_ghcb_pg;
extern bool hv_isolation_type_en_snp(void);
/*
* 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);
@ -256,12 +262,14 @@ void hv_ghcb_msr_read(u64 msr, u64 *value);
bool hv_ghcb_negotiate_protocol(void);
void __noreturn hv_ghcb_terminate(unsigned int set, unsigned int reason);
void hv_vtom_init(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) {}
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 int hv_snp_boot_ap(int cpu, unsigned long start_ip) { return 0; }
#endif
extern bool hv_isolation_type_snp(void);

11
arch/x86/kernel/cpu/mshyperv.c
View File

@ -295,6 +295,15 @@ static void __init hv_smp_prepare_cpus(unsigned int max_cpus)
native_smp_prepare_cpus(max_cpus);
/*
* Override wakeup_secondary_cpu_64 callback for SEV-SNP
* enlightened guest.
*/
if (hv_isolation_type_en_snp()) {
apic->wakeup_secondary_cpu_64 = hv_snp_boot_ap;
return;
}
#ifdef CONFIG_X86_64
for_each_present_cpu(i) {
if (i == 0)
@ -502,7 +511,7 @@ 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)
if (hv_root_partition || hv_isolation_type_en_snp())
smp_ops.smp_prepare_cpus = hv_smp_prepare_cpus;
# endif

1
include/asm-generic/hyperv-tlfs.h
View File

@ -223,6 +223,7 @@ 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 120
#define HV_STATUS_VTL_ALREADY_ENABLED 134
/*