On 2/11/2025 2:21 PM, Nuno Das Neves wrote: > Introduce CONFIG_MSHV_ROOT as a tristate to enable root partition > booting and future mshv driver functionality. > > Change hv_root_partition into a function which always returns false > if CONFIG_MSHV_ROOT=n. > > Introduce hv_current_partition_type to store the type of partition > (guest, root, or other kinds in future), and hv_identify_partition_type() > to it up early in Hyper-V initialization. ...to *set* it up early? > > Signed-off-by: Nuno Das Neves <nunodasneves@xxxxxxxxxxxxxxxxxxx> > --- > Depends on > https://lore.kernel.org/linux-hyperv/1738955002-20821-3-git-send-email-nunodasneves@xxxxxxxxxxxxxxxxxxx/ > > arch/arm64/hyperv/mshyperv.c | 2 ++ > arch/x86/hyperv/hv_init.c | 10 ++++---- > arch/x86/kernel/cpu/mshyperv.c | 24 ++---------------- > drivers/clocksource/hyperv_timer.c | 4 +-- > drivers/hv/Kconfig | 12 +++++++++ > drivers/hv/Makefile | 3 ++- > drivers/hv/hv.c | 10 ++++---- > drivers/hv/hv_common.c | 32 +++++++++++++++++++----- > drivers/hv/vmbus_drv.c | 2 +- > drivers/iommu/hyperv-iommu.c | 4 +-- > include/asm-generic/mshyperv.h | 39 +++++++++++++++++++++++++----- > 11 files changed, 92 insertions(+), 50 deletions(-) > <snip> > + > +void hv_identify_partition_type(void) > +{ > + /* > + * Check partition creation and cpu management privileges > + * > + * Hyper-V should never specify running as root and as a Confidential > + * VM. But to protect against a compromised/malicious Hyper-V trying > + * to exploit root behavior to expose Confidential VM memory, ignore > + * the root partition setting if also a Confidential VM. > + */ > + if ((ms_hyperv.priv_high & HV_CREATE_PARTITIONS) && > + (ms_hyperv.priv_high & HV_CPU_MANAGEMENT) && > + !(ms_hyperv.priv_high & HV_ISOLATION)) { > + hv_current_partition_type = HV_PARTITION_TYPE_ROOT; > + pr_info("Hyper-V: running as root partition\n"); > + } else { > + hv_current_partition_type = HV_PARTITION_TYPE_GUEST; > + } > +} This should assume GUEST as default and modify to ROOT if all the checks pass. <snip> > +static inline int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages) > +{ > + return hv_result(U64_MAX); > +} Is there value in perhaps #defining hv_result_<whatever this is> as U64_MAX and returning that for documentation? For e.g. assuming this is something like EOPNOTSUPP #define HV_RESULT_NOT_SUPP U64_MAX static inline int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages) { return hv_result(HV_RESULT_NOT_SUPP); } <snip> Thanks, Easwar (he/him)
