From 44676bb9d566ce2bfbd132f9745eb7eb2d784476 Mon Sep 17 00:00:00 2001 From: Tianyu Lan Date: Fri, 18 Aug 2023 06:29:17 -0400 Subject: [PATCH] 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 Reviewed-by: Michael Kelley Signed-off-by: Tianyu Lan Signed-off-by: Wei Liu Link: https://lore.kernel.org/r/20230818102919.1318039-8-ltykernel@gmail.com --- arch/x86/hyperv/ivm.c | 138 ++++++++++++++++++++++++++++++++++++++ arch/x86/include/asm/mshyperv.h | 8 +++ arch/x86/kernel/cpu/mshyperv.c | 11 ++- include/asm-generic/hyperv-tlfs.h | 1 + 4 files changed, 157 insertions(+), 1 deletion(-) diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c index b2b5cb1..cbbd3af 100644 --- a/arch/x86/hyperv/ivm.c +++ b/arch/x86/hyperv/ivm.c @@ -18,11 +18,20 @@ #include #include #include +#include +#include +#include +#include +#include +#include #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) { /* diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h index 8660d6b..6bd9ae0 100644 --- a/arch/x86/include/asm/mshyperv.h +++ b/arch/x86/include/asm/mshyperv.h @@ -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); diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index 5398fb2..c56fc15 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -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 diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h index f4e4cc4..fdac4a1 100644 --- a/include/asm-generic/hyperv-tlfs.h +++ b/include/asm-generic/hyperv-tlfs.h @@ -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 /* -- 2.7.4