From: Nuno Das Neves <nunodasneves@xxxxxxxxxxxxxxxxxxx> Sent: Friday, December 6, 2024 2:22 PM > > Make hv_current_partition_id available in both x86_64 and arm64. > This feature isn't specific to x86_64 and will be needed by common > code. > > While at it, replace the BUG()s with WARN()s. Failing to get the id > need not crash the machine (although it is a very bad sign). > > Signed-off-by: Nuno Das Neves <nudasnev@xxxxxxxxxxxxx> > --- > arch/arm64/hyperv/mshyperv.c | 3 +++ > arch/x86/hyperv/hv_init.c | 25 +------------------------ > arch/x86/include/asm/mshyperv.h | 2 -- > drivers/hv/hv_common.c | 23 +++++++++++++++++++++++ > include/asm-generic/mshyperv.h | 2 ++ > 5 files changed, 29 insertions(+), 26 deletions(-) > > diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c > index b1a4de4eee29..5050e748d266 100644 > --- a/arch/arm64/hyperv/mshyperv.c > +++ b/arch/arm64/hyperv/mshyperv.c > @@ -19,6 +19,9 @@ > > static bool hyperv_initialized; > > +u64 hv_current_partition_id = HV_PARTITION_ID_SELF; > +EXPORT_SYMBOL_GPL(hv_current_partition_id); > + Instead of adding a definition of hv_current_partition_id on the arm64 side, couldn't the definition on the x86 side in hv_init.c be moved to hv_common.c (or maybe somewhere else that is specific to running in the root partition, per my comments in the cover letter), so there is only one definition shared by both architectures? > int hv_get_hypervisor_version(union hv_hypervisor_version_info *info) > { > hv_get_vpreg_128(HV_REGISTER_HYPERVISOR_VERSION, > diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c > index 95eada2994e1..950f5ccdb9d9 100644 > --- a/arch/x86/hyperv/hv_init.c > +++ b/arch/x86/hyperv/hv_init.c > @@ -35,7 +35,7 @@ > #include <clocksource/hyperv_timer.h> > #include <linux/highmem.h> > > -u64 hv_current_partition_id = ~0ull; > +u64 hv_current_partition_id = HV_PARTITION_ID_SELF; > EXPORT_SYMBOL_GPL(hv_current_partition_id); > > void *hv_hypercall_pg; > @@ -394,24 +394,6 @@ static void __init hv_stimer_setup_percpu_clockev(void) > old_setup_percpu_clockev(); > } > > -static void __init hv_get_partition_id(void) > -{ > - struct hv_get_partition_id *output_page; > - u64 status; > - unsigned long flags; > - > - local_irq_save(flags); > - output_page = *this_cpu_ptr(hyperv_pcpu_output_arg); > - status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page); > - if (!hv_result_success(status)) { > - /* No point in proceeding if this failed */ > - pr_err("Failed to get partition ID: %lld\n", status); > - BUG(); > - } > - hv_current_partition_id = output_page->partition_id; > - local_irq_restore(flags); > -} > - > #if IS_ENABLED(CONFIG_HYPERV_VTL_MODE) > static u8 __init get_vtl(void) > { > @@ -606,11 +588,6 @@ void __init hyperv_init(void) > > register_syscore_ops(&hv_syscore_ops); > > - if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_ACCESS_PARTITION_ID) > - hv_get_partition_id(); > - > - BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull); > - > #ifdef CONFIG_PCI_MSI > /* > * If we're running as root, we want to create our own PCI MSI domain. > diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h > index 5f0bc6a6d025..9eeca2a6d047 100644 > --- a/arch/x86/include/asm/mshyperv.h > +++ b/arch/x86/include/asm/mshyperv.h > @@ -44,8 +44,6 @@ extern bool hyperv_paravisor_present; > > extern void *hv_hypercall_pg; > > -extern u64 hv_current_partition_id; > - > extern union hv_ghcb * __percpu *hv_ghcb_pg; > > bool hv_isolation_type_snp(void); > diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c > index 7a35c82976e0..819bcfd2b149 100644 > --- a/drivers/hv/hv_common.c > +++ b/drivers/hv/hv_common.c > @@ -278,11 +278,34 @@ static void hv_kmsg_dump_register(void) > } > } > > +static void __init hv_get_partition_id(void) > +{ > + struct hv_get_partition_id *output_page; > + u64 status; > + unsigned long flags; > + > + local_irq_save(flags); > + output_page = *this_cpu_ptr(hyperv_pcpu_output_arg); > + status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page); > + if (!hv_result_success(status)) { > + local_irq_restore(flags); > + WARN(true, "Failed to get partition ID: %lld\n", status); > + return; > + } > + hv_current_partition_id = output_page->partition_id; > + local_irq_restore(flags); > +} > + > int __init hv_common_init(void) > { > int i; > union hv_hypervisor_version_info version; > > + if (ms_hyperv.priv_high & HV_ACCESS_PARTITION_ID) > + hv_get_partition_id(); hv_get_partition_id() uses the hyperv_pcpu_output_arg, and at this point, hyperv_pcpu_output_arg isn't set. That setup is done later in hv_common_init(). > + > + WARN_ON(hv_root_partition && hv_current_partition_id == HV_PARTITION_ID_SELF); > + Since the hypercall will fail cleanly if the calling VM doesn't have the HV_ACCESS_PARTITION_ID privilege, could the above be simplified to just this? if (hv_root_partition) hv_get_partition_id(): A non-root partition VM doesn't need to get the partition ID, while a root partition should have the privilege. If the hypercall fails, there's already a WARN, so there's no value in doing another WARN. Also if the hypercall succeeds, it presumably returns a specific partitionID, not HV_PARTITION_ID_SELF, so we know we have what we want. There's already an "if (hv_root_partition)" statement for setting up the hyperv_pcpu_output_arg. The call to hv_get_partition_id() could go under that existing "if" *after* the hyperv_pcpu_output_arg is set. :-) Michael > /* Get information about the Hyper-V host version */ > if (!hv_get_hypervisor_version(&version)) > pr_info("Hyper-V: Host Build %d.%d.%d.%d-%d-%d\n", > diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h > index 8fe7aaab2599..8c4ff6e9aae7 100644 > --- a/include/asm-generic/mshyperv.h > +++ b/include/asm-generic/mshyperv.h > @@ -60,6 +60,8 @@ struct ms_hyperv_info { > extern struct ms_hyperv_info ms_hyperv; > extern bool hv_nested; > > +extern u64 hv_current_partition_id; > + > extern void * __percpu *hyperv_pcpu_input_arg; > extern void * __percpu *hyperv_pcpu_output_arg; > > -- > 2.34.1