Commit 0cc4f6d9 authored by Tianyu Lan's avatar Tianyu Lan Committed by Wei Liu
Browse files

x86/hyperv: Initialize GHCB page in Isolation VM 



Hyperv exposes GHCB page via SEV ES GHCB MSR for SNP guest
to communicate with hypervisor. Map GHCB page for all
cpus to read/write MSR register and submit hvcall request
via ghcb page.

Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Signed-off-by: default avatarTianyu Lan <Tianyu.Lan@microsoft.com>
Link: https://lore.kernel.org/r/20211025122116.264793-2-ltykernel@gmail.com


Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
parent e82f2069

arch/x86/hyperv/hv_init.c

+61 −7
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/kexec.h>

#include <linux/version.h>

#include <linux/vmalloc.h>

#include <linux/io.h>

#include <linux/mm.h>

#include <linux/hyperv.h>

#include <linux/slab.h>
@@ -36,12 +37,42 @@ EXPORT_SYMBOL_GPL(hv_current_partition_id); 
void *hv_hypercall_pg;

EXPORT_SYMBOL_GPL(hv_hypercall_pg);



void __percpu **hv_ghcb_pg;



/* Storage to save the hypercall page temporarily for hibernation */

static void *hv_hypercall_pg_saved;



struct hv_vp_assist_page **hv_vp_assist_page;

EXPORT_SYMBOL_GPL(hv_vp_assist_page);



static int hyperv_init_ghcb(void)

{

	u64 ghcb_gpa;

	void *ghcb_va;

	void **ghcb_base;



	if (!hv_isolation_type_snp())

		return 0;



	if (!hv_ghcb_pg)

		return -EINVAL;



	/*

	 * GHCB page is allocated by paravisor. The address

	 * returned by MSR_AMD64_SEV_ES_GHCB is above shared

	 * memory boundary and map it here.

	 */

	rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);

	ghcb_va = memremap(ghcb_gpa, HV_HYP_PAGE_SIZE, MEMREMAP_WB);

	if (!ghcb_va)

		return -ENOMEM;



	ghcb_base = (void **)this_cpu_ptr(hv_ghcb_pg);

	*ghcb_base = ghcb_va;



	return 0;

}



static int hv_cpu_init(unsigned int cpu)

{

	union hv_vp_assist_msr_contents msr = { 0 };
@@ -85,7 +116,7 @@ static int hv_cpu_init(unsigned int cpu) 
		}

	}



	return 0;

	return hyperv_init_ghcb();

}



static void (*hv_reenlightenment_cb)(void);
@@ -177,6 +208,14 @@ static int hv_cpu_die(unsigned int cpu) 
{

	struct hv_reenlightenment_control re_ctrl;

	unsigned int new_cpu;

	void **ghcb_va;



	if (hv_ghcb_pg) {

		ghcb_va = (void **)this_cpu_ptr(hv_ghcb_pg);

		if (*ghcb_va)

			memunmap(*ghcb_va);

		*ghcb_va = NULL;

	}



	hv_common_cpu_die(cpu);
@@ -366,10 +405,16 @@ void __init hyperv_init(void) 
		goto common_free;

	}



	if (hv_isolation_type_snp()) {

		hv_ghcb_pg = alloc_percpu(void *);

		if (!hv_ghcb_pg)

			goto free_vp_assist_page;

	}



	cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",

				  hv_cpu_init, hv_cpu_die);

	if (cpuhp < 0)

		goto free_vp_assist_page;

		goto free_ghcb_page;



	/*

	 * Setup the hypercall page and enable hypercalls.
@@ -383,10 +428,8 @@ void __init hyperv_init(void) 
			VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,

			VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,

			__builtin_return_address(0));

	if (hv_hypercall_pg == NULL) {

		wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);

		goto remove_cpuhp_state;

	}

	if (hv_hypercall_pg == NULL)

		goto clean_guest_os_id;



	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

	hypercall_msr.enable = 1;
@@ -456,8 +499,11 @@ void __init hyperv_init(void) 
	hv_query_ext_cap(0);

	return;



remove_cpuhp_state:

clean_guest_os_id:

	wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);

	cpuhp_remove_state(cpuhp);

free_ghcb_page:

	free_percpu(hv_ghcb_pg);

free_vp_assist_page:

	kfree(hv_vp_assist_page);

	hv_vp_assist_page = NULL;
@@ -559,3 +605,11 @@ bool hv_is_isolation_supported(void) 
{

	return hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE;

}



DEFINE_STATIC_KEY_FALSE(isolation_type_snp);



bool hv_isolation_type_snp(void)

{

	return static_branch_unlikely(&isolation_type_snp);

}

EXPORT_SYMBOL_GPL(hv_isolation_type_snp);

arch/x86/include/asm/mshyperv.h

+4 −0
Original line number Diff line number Diff line
@@ -11,6 +11,8 @@ 
#include <asm/paravirt.h>

#include <asm/mshyperv.h>



DECLARE_STATIC_KEY_FALSE(isolation_type_snp);



typedef int (*hyperv_fill_flush_list_func)(

		struct hv_guest_mapping_flush_list *flush,

		void *data);
@@ -39,6 +41,8 @@ extern void *hv_hypercall_pg; 


extern u64 hv_current_partition_id;



extern void __percpu **hv_ghcb_pg;



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);

arch/x86/kernel/cpu/mshyperv.c

+3 −0
Original line number Diff line number Diff line
@@ -316,6 +316,9 @@ static void __init ms_hyperv_init_platform(void) 


		pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n",

			ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);



		if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP)

			static_branch_enable(&isolation_type_snp);

	}



	if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) {

include/asm-generic/mshyperv.h

+6 −0
Original line number Diff line number Diff line
@@ -254,12 +254,18 @@ bool hv_is_hyperv_initialized(void); 
bool hv_is_hibernation_supported(void);

enum hv_isolation_type hv_get_isolation_type(void);

bool hv_is_isolation_supported(void);

bool hv_isolation_type_snp(void);

void hyperv_cleanup(void);

bool hv_query_ext_cap(u64 cap_query);

#else /* CONFIG_HYPERV */

static inline bool hv_is_hyperv_initialized(void) { return false; }

static inline bool hv_is_hibernation_supported(void) { return false; }

static inline void hyperv_cleanup(void) {}

static inline bool hv_is_isolation_supported(void) { return false; }

static inline enum hv_isolation_type hv_get_isolation_type(void)

{

	return HV_ISOLATION_TYPE_NONE;

}

#endif /* CONFIG_HYPERV */



#endif