diff options
| author | Nuno Das Neves <nunodasneves@linux.microsoft.com> | 2025-02-21 11:56:35 -0800 |
|---|---|---|
| committer | Wei Liu <wei.liu@kernel.org> | 2025-03-20 21:22:58 +0000 |
| commit | 461fbbd036b11d755b50e2ef7c165859a0f908d5 (patch) | |
| tree | caa25ffab490e20c17207d34de3c6543deae1564 /drivers/hv | |
| parent | db912b8954c23a55dbc6dc683e0e06ffcb433848 (diff) | |
hyperv: Add CONFIG_MSHV_ROOT to gate root partition support
CONFIG_MSHV_ROOT allows kernels built to run as a normal Hyper-V guest
to exclude the root partition code, which is expected to grow
significantly over time.
This option is a tristate so future driver code can be built as a
(m)odule, allowing faster development iteration cycles.
If CONFIG_MSHV_ROOT is disabled, don't compile hv_proc.c, and stub
hv_root_partition() to return false unconditionally. This allows the
compiler to optimize away root partition code blocks since they will
be disabled at compile time.
In the case of booting as root partition *without* CONFIG_MSHV_ROOT
enabled, print a critical error (the kernel will likely crash).
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/1740167795-13296-4-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1740167795-13296-4-git-send-email-nunodasneves@linux.microsoft.com>
Diffstat (limited to 'drivers/hv')
| -rw-r--r-- | drivers/hv/Kconfig | 16 | ||||
| -rw-r--r-- | drivers/hv/Makefile | 3 | ||||
| -rw-r--r-- | drivers/hv/hv_common.c | 5 |
3 files changed, 22 insertions, 2 deletions
diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig index 862c47b191af..3118d5472fab 100644 --- a/drivers/hv/Kconfig +++ b/drivers/hv/Kconfig @@ -55,4 +55,20 @@ config HYPERV_BALLOON help Select this option to enable Hyper-V Balloon driver. +config MSHV_ROOT + tristate "Microsoft Hyper-V root partition support" + depends on HYPERV && (X86_64 || ARM64) + depends on !HYPERV_VTL_MODE + # The hypervisor interface operates on 4k pages. Enforcing it here + # simplifies many assumptions in the root partition code. + # e.g. When withdrawing memory, the hypervisor gives back 4k pages in + # no particular order, making it impossible to reassemble larger pages + depends on PAGE_SIZE_4KB + default n + help + Select this option to enable support for booting and running as root + partition on Microsoft Hyper-V. + + If unsure, say N. + endmenu diff --git a/drivers/hv/Makefile b/drivers/hv/Makefile index 9afcabb3fbd2..2b8dc954b350 100644 --- a/drivers/hv/Makefile +++ b/drivers/hv/Makefile @@ -13,4 +13,5 @@ hv_vmbus-$(CONFIG_HYPERV_TESTING) += hv_debugfs.o hv_utils-y := hv_util.o hv_kvp.o hv_snapshot.o hv_utils_transport.o # Code that must be built-in -obj-$(subst m,y,$(CONFIG_HYPERV)) += hv_common.o hv_proc.o +obj-$(subst m,y,$(CONFIG_HYPERV)) += hv_common.o +obj-$(subst m,y,$(CONFIG_MSHV_ROOT)) += hv_proc.o diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c index 3d9cfcfbc854..9804adb4cc56 100644 --- a/drivers/hv/hv_common.c +++ b/drivers/hv/hv_common.c @@ -734,6 +734,9 @@ void hv_identify_partition_type(void) (ms_hyperv.priv_high & HV_CPU_MANAGEMENT) && !(ms_hyperv.priv_high & HV_ISOLATION)) { pr_info("Hyper-V: running as root partition\n"); - hv_curr_partition_type = HV_PARTITION_TYPE_ROOT; + if (IS_ENABLED(CONFIG_MSHV_ROOT)) + hv_curr_partition_type = HV_PARTITION_TYPE_ROOT; + else + pr_crit("Hyper-V: CONFIG_MSHV_ROOT not enabled!\n"); } } |