diff options
Diffstat (limited to 'drivers/hv')
| -rw-r--r-- | drivers/hv/Makefile | 3 | ||||
| -rw-r--r-- | drivers/hv/hv_common.c | 66 |
2 files changed, 69 insertions, 0 deletions
diff --git a/drivers/hv/Makefile b/drivers/hv/Makefile index 94daf8240c95..d76df5c8c2a9 100644 --- a/drivers/hv/Makefile +++ b/drivers/hv/Makefile @@ -11,3 +11,6 @@ hv_vmbus-y := vmbus_drv.o \ channel_mgmt.o ring_buffer.o hv_trace.o hv_vmbus-$(CONFIG_HYPERV_TESTING) += hv_debugfs.o hv_utils-y := hv_util.o hv_kvp.o hv_snapshot.o hv_fcopy.o hv_utils_transport.o + +# Code that must be built-in +obj-$(subst m,y,$(CONFIG_HYPERV)) += hv_common.o diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c new file mode 100644 index 000000000000..f0053c786891 --- /dev/null +++ b/drivers/hv/hv_common.c @@ -0,0 +1,66 @@ +// 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 <mikelley@microsoft.com> + */ + +#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 imcompatible 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, + &hv_extended_cap); + + /* + * 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", + status); + return false; + } + + return hv_extended_cap & cap_query; +} +EXPORT_SYMBOL_GPL(hv_query_ext_cap); |