Commit 44676bb9 authored by Tianyu Lan's avatar Tianyu Lan Committed by Wei Liu
Browse files

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: default avatarDexuan Cui <decui@microsoft.com>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Signed-off-by: default avatarTianyu Lan <tiala@microsoft.com>
Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
Link: https://lore.kernel.org/r/20230818102919.1318039-8-ltykernel@gmail.com
parent 45f46b1a

arch/x86/hyperv/ivm.c

+138 −0
Original line number Diff line number Diff line
@@ -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)

{

	/*

arch/x86/include/asm/mshyperv.h

+8 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/kernel/cpu/mshyperv.c

+10 −1
Original line number Diff line number Diff line
@@ -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

include/asm-generic/hyperv-tlfs.h

+1 −0
Original line number Diff line number Diff line
@@ -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



/*