blob: 7f42da98d377e0f369ad3661368cf0c65cd57356 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
* Architecture neutral utility routines for interacting with
* Hyper-V. This file is specifically for code that must be
* built-in to the kernel image when CONFIG_HYPERV is set
* (vs. being in a module) because it is called from architecture
* specific code under arch/.
* Copyright (C) 2021, Microsoft, Inc.
* Author : Michael Kelley <>
#include <linux/types.h>
#include <linux/export.h>
#include <linux/bitfield.h>
#include <asm/hyperv-tlfs.h>
#include <asm/mshyperv.h>
/* Bit mask of the extended capability to query: see HV_EXT_CAPABILITY_xxx */
bool hv_query_ext_cap(u64 cap_query)
* The address of the 'hv_extended_cap' variable will be used as an
* output parameter to the hypercall below and so it should be
* compatible with 'virt_to_phys'. Which means, it's address should be
* directly mapped. Use 'static' to keep it compatible; stack variables
* can be virtually mapped, making them incompatible with
* 'virt_to_phys'.
* Hypercall input/output addresses should also be 8-byte aligned.
static u64 hv_extended_cap __aligned(8);
static bool hv_extended_cap_queried;
u64 status;
* Querying extended capabilities is an extended hypercall. Check if the
* partition supports extended hypercall, first.
if (!(ms_hyperv.priv_high & HV_ENABLE_EXTENDED_HYPERCALLS))
return false;
/* Extended capabilities do not change at runtime. */
if (hv_extended_cap_queried)
return hv_extended_cap & cap_query;
status = hv_do_hypercall(HV_EXT_CALL_QUERY_CAPABILITIES, NULL,
* The query extended capabilities hypercall should not fail under
* any normal circumstances. Avoid repeatedly making the hypercall, on
* error.
hv_extended_cap_queried = true;
if (!hv_result_success(status)) {
pr_err("Hyper-V: Extended query capabilities hypercall failed 0x%llx\n",
return false;
return hv_extended_cap & cap_query;