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| author |  Jinank Jain <jinankjain@linux.microsoft.com>
| 2023-01-02 07:12:51 +0000 |
|---|---|---|
| committer |  Wei Liu <wei.liu@kernel.org>
| 2023-01-12 15:23:26 +0000 |
| commit | c4bdf94f97c86bdee8bacc87f8f85dc67866c928 (patch) | |
| tree | 0fb80013913a5eb1966a31e39e7771120cdcb7e9 | |
| parent | Linux 6.2-rc3 (diff) | |
| download | linux-c4bdf94f97c86bdee8bacc87f8f85dc67866c928.tar.gz linux-c4bdf94f97c86bdee8bacc87f8f85dc67866c928.tar.bz2 linux-c4bdf94f97c86bdee8bacc87f8f85dc67866c928.zip | |
x86/hyperv: Add support for detecting nested hypervisor
Detect if Linux is running as a nested hypervisor in the root
partition for Microsoft Hypervisor, using flags provided by MSHV.
Expose a new variable hv_nested that is used later for decisions
specific to the nested use case.
Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/8e3e7112806e81d2292a66a56fe547162754ecea.1672639707.git.jinankjain@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
| -rw-r--r-- | arch/x86/include/asm/hyperv-tlfs.h | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/mshyperv.c | 7 | ||||
| -rw-r--r-- | drivers/hv/hv_common.c | 9 | ||||
| -rw-r--r-- | include/asm-generic/mshyperv.h | 1 |
4 files changed, 17 insertions, 3 deletions
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h index 08e822bd7aa6..724a2589c0e7 100644 --- a/arch/x86/include/asm/hyperv-tlfs.h +++ b/arch/x86/include/asm/hyperv-tlfs.h @@ -116,6 +116,9 @@ /* Recommend using the newer ExProcessorMasks interface */ #define HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED BIT(11) +/* Indicates that the hypervisor is nested within a Hyper-V partition. */ +#define HV_X64_HYPERV_NESTED BIT(12) + /* Recommend using enlightened VMCS */ #define HV_X64_ENLIGHTENED_VMCS_RECOMMENDED BIT(14) diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index 46668e255421..f9b78d4829e3 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -37,6 +37,8 @@ /* Is Linux running as the root partition? */ bool hv_root_partition; +/* Is Linux running on nested Microsoft Hypervisor */ +bool hv_nested; struct ms_hyperv_info ms_hyperv; #if IS_ENABLED(CONFIG_HYPERV) @@ -301,6 +303,11 @@ static void __init ms_hyperv_init_platform(void) pr_info("Hyper-V: running as root partition\n"); } + if (ms_hyperv.hints & HV_X64_HYPERV_NESTED) { + hv_nested = true; + pr_info("Hyper-V: running on a nested hypervisor\n"); + } + /* * Extract host information. */ diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c index ae68298c0dca..52a6f89ccdbd 100644 --- a/drivers/hv/hv_common.c +++ b/drivers/hv/hv_common.c @@ -25,17 +25,20 @@ #include <asm/mshyperv.h> /* - * hv_root_partition and ms_hyperv are defined here with other Hyper-V - * specific globals so they are shared across all architectures and are + * hv_root_partition, ms_hyperv and hv_nested are defined here with other + * Hyper-V specific globals so they are shared across all architectures and are * built only when CONFIG_HYPERV is defined. But on x86, * ms_hyperv_init_platform() is built even when CONFIG_HYPERV is not - * defined, and it uses these two variables. So mark them as __weak + * defined, and it uses these three variables. So mark them as __weak * here, allowing for an overriding definition in the module containing * ms_hyperv_init_platform(). */ bool __weak hv_root_partition; EXPORT_SYMBOL_GPL(hv_root_partition); +bool __weak hv_nested; +EXPORT_SYMBOL_GPL(hv_nested); + struct ms_hyperv_info __weak ms_hyperv; EXPORT_SYMBOL_GPL(ms_hyperv); diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h index d55d2833a37b..8845a2eca339 100644 --- a/include/asm-generic/mshyperv.h +++ b/include/asm-generic/mshyperv.h @@ -48,6 +48,7 @@ struct ms_hyperv_info { u64 shared_gpa_boundary; }; extern struct ms_hyperv_info ms_hyperv; +extern bool hv_nested; extern void * __percpu *hyperv_pcpu_input_arg; extern void * __percpu *hyperv_pcpu_output_arg; |