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    SubjectRE: [RFC PATCH V3 10/16] x86/hyperv: Add smp support for sev-snp guest
    Date
    From: Tianyu Lan <ltykernel@gmail.com> Sent: Saturday, January 21, 2023 6:46 PM
    >
    > The wakeup_secondary_cpu callback was populated with wakeup_
    > cpu_via_vmgexit() which doesn't work for Hyper-V. Override it
    > with Hyper-V specific hook which uses HVCALL_START_VIRTUAL_
    > PROCESSOR hvcall to start AP with vmsa data structure.
    >
    > Signed-off-by: Tianyu Lan <tiala@microsoft.com>
    > ---
    > Change since RFC v2:
    > * Add helper function to initialize segment
    > * Fix some coding style
    > ---
    > arch/x86/include/asm/mshyperv.h | 2 +
    > arch/x86/include/asm/sev.h | 13 ++++
    > arch/x86/include/asm/svm.h | 47 +++++++++++++
    > arch/x86/kernel/cpu/mshyperv.c | 112 ++++++++++++++++++++++++++++--
    > include/asm-generic/hyperv-tlfs.h | 19 +++++
    > 5 files changed, 189 insertions(+), 4 deletions(-)
    >
    > diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
    > index 7266d71d30d6..c69051eec0e1 100644
    > --- a/arch/x86/include/asm/mshyperv.h
    > +++ b/arch/x86/include/asm/mshyperv.h
    > @@ -203,6 +203,8 @@ 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);
    > 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..f8b321a11ee4 100644
    > --- a/arch/x86/include/asm/svm.h
    > +++ b/arch/x86/include/asm/svm.h
    > @@ -336,6 +336,53 @@ struct vmcb_save_area {
    > u64 last_excp_to;
    > u8 reserved_0x298[72];
    > u32 spec_ctrl; /* Guest version of SPEC_CTRL at 0x2E0 */
    > + u8 reserved_7b[4];
    > + u32 pkru;
    > + u8 reserved_7a[20];
    > + u64 reserved_8; /* rax already available at 0x01f8 */
    > + u64 rcx;
    > + u64 rdx;
    > + u64 rbx;
    > + u64 reserved_9; /* rsp already available at 0x01d8 */
    > + u64 rbp;
    > + u64 rsi;
    > + u64 rdi;
    > + u64 r8;
    > + u64 r9;
    > + u64 r10;
    > + u64 r11;
    > + u64 r12;
    > + u64 r13;
    > + u64 r14;
    > + u64 r15;
    > + u8 reserved_10[16];
    > + u64 sw_exit_code;
    > + u64 sw_exit_info_1;
    > + u64 sw_exit_info_2;
    > + u64 sw_scratch;
    > + union {
    > + u64 sev_features;
    > + struct {
    > + u64 sev_feature_snp : 1;
    > + u64 sev_feature_vtom : 1;
    > + u64 sev_feature_reflectvc : 1;
    > + u64 sev_feature_restrict_injection : 1;
    > + u64 sev_feature_alternate_injection : 1;
    > + u64 sev_feature_full_debug : 1;
    > + u64 sev_feature_reserved1 : 1;
    > + u64 sev_feature_snpbtb_isolation : 1;
    > + u64 sev_feature_resrved2 : 56;
    > + };
    > + };
    > + u64 vintr_ctrl;
    > + u64 guest_error_code;
    > + u64 virtual_tom;
    > + u64 tlb_id;
    > + u64 pcpu_id;
    > + u64 event_inject;
    > + u64 xcr0;
    > + u8 valid_bitmap[16];
    > + u64 x87_state_gpa;
    > } __packed;
    >
    > /* Save area definition for SEV-ES and SEV-SNP guests */
    > diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
    > index 197c8f2ec4eb..9d547751a1a7 100644
    > --- a/arch/x86/kernel/cpu/mshyperv.c
    > +++ b/arch/x86/kernel/cpu/mshyperv.c
    > @@ -39,6 +39,13 @@
    > #include <asm/realmode.h>
    > #include <asm/e820/api.h>
    >
    > +/*
    > + * 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

    If these values are defined by Hyper-V, they should probably go in
    hyperv-tlfs.h.

    > +
    > /* Is Linux running as the root partition? */
    > bool hv_root_partition;
    > struct ms_hyperv_info ms_hyperv;
    > @@ -230,6 +237,94 @@ static void __init hv_smp_prepare_boot_cpu(void)
    > #endif
    > }
    >
    > +static u8 ap_start_input_arg[PAGE_SIZE] __bss_decrypted __aligned(PAGE_SIZE);
    > +static u8 ap_start_stack[PAGE_SIZE] __aligned(PAGE_SIZE);
    > +
    > +#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 vmcb_save_area *vmsa = (struct vmcb_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_feature_snp = 1;
    > + vmsa->sev_feature_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;
    > +}
    > +

    Like a comment in an earlier patch, I'm wondering if the bulk of
    this code could move to ivm.c, to avoid overloading mshyperv.c.

    > static void __init hv_smp_prepare_cpus(unsigned int max_cpus)
    > {
    > #ifdef CONFIG_X86_64
    > @@ -239,6 +334,16 @@ 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)
    > @@ -475,8 +580,7 @@ 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
    >
    > /*
    > @@ -501,7 +605,7 @@ static void __init ms_hyperv_init_platform(void)
    > if (!(ms_hyperv.features & HV_ACCESS_TSC_INVARIANT))
    > mark_tsc_unstable("running on Hyper-V");
    >
    > - if (isolation_type_en_snp()) {
    > + if (hv_isolation_type_en_snp()) {

    Also a bug fix to an earlier patch in this series.

    > /*
    > * Hyper-V enlightened snp guest boots kernel
    > * directly without bootloader and so roms,
    > @@ -511,7 +615,7 @@ static void __init ms_hyperv_init_platform(void)
    > x86_platform.legacy.rtc = 0;
    > x86_platform.set_wallclock = set_rtc_noop;
    > x86_platform.get_wallclock = get_rtc_noop;
    > - x86_platform.legacy.reserve_bios_regions = x86_init_noop;
    > + x86_platform.legacy.reserve_bios_regions = 0;

    This looks like a bug fix to Patch 8 of the series. It should be fixed
    in patch 8.

    > x86_init.resources.probe_roms = x86_init_noop;
    > x86_init.resources.reserve_resources = x86_init_noop;
    > x86_init.mpparse.find_smp_config = x86_init_noop;
    > diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
    > index c1cc3ec36ad5..3d7c67be9f56 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
    > @@ -219,6 +221,7 @@ 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
    > @@ -778,6 +781,22 @@ 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

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