Michael Kelley
2021-Jan-26 00:48 UTC
[PATCH v5 07/16] x86/hyperv: extract partition ID from Microsoft Hypervisor if necessary
From: Wei Liu <wei.liu at kernel.org> Sent: Wednesday, January 20, 2021 4:01 AM> > We will need the partition ID for executing some hypercalls later. > > Signed-off-by: Lillian Grassin-Drake <ligrassi at microsoft.com> > Co-Developed-by: Sunil Muthuswamy <sunilmut at microsoft.com> > Signed-off-by: Wei Liu <wei.liu at kernel.org> > --- > v3: > 1. Make hv_get_partition_id static. > 2. Change code structure a bit. > --- > arch/x86/hyperv/hv_init.c | 27 +++++++++++++++++++++++++++ > arch/x86/include/asm/mshyperv.h | 2 ++ > include/asm-generic/hyperv-tlfs.h | 6 ++++++ > 3 files changed, 35 insertions(+) > > diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c > index 6f4cb40e53fe..fc9941bd8653 100644 > --- a/arch/x86/hyperv/hv_init.c > +++ b/arch/x86/hyperv/hv_init.c > @@ -26,6 +26,9 @@ > #include <linux/syscore_ops.h> > #include <clocksource/hyperv_timer.h> > > +u64 hv_current_partition_id = ~0ull; > +EXPORT_SYMBOL_GPL(hv_current_partition_id); > + > void *hv_hypercall_pg; > EXPORT_SYMBOL_GPL(hv_hypercall_pg); > > @@ -331,6 +334,25 @@ static struct syscore_ops hv_syscore_ops = { > .resume = hv_resume, > }; > > +static void __init hv_get_partition_id(void) > +{ > + struct hv_get_partition_id *output_page; > + u16 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) & > + HV_HYPERCALL_RESULT_MASK; > + if (status != HV_STATUS_SUCCESS) {Across the Hyper-V code in Linux, the way we check the hypercall result is very inconsistent. IMHO, the and'ing of hv_do_hypercall() with HV_HYPERCALL_RESULT_MASK so that status can be a u16 is stylistically a bit unusual. I'd like to see the hypercall result being stored into a u64 local variable. Then the subsequent test for the status should 'and' the u64 with HV_HYPERCALL_RESULT_MASK to determine the result code. I've made a note to go fix the places that aren't doing it that way.> + /* No point in proceeding if this failed */ > + pr_err("Failed to get partition ID: %d\n", status); > + BUG(); > + } > + hv_current_partition_id = output_page->partition_id; > + local_irq_restore(flags); > +} > + > /* > * This function is to be invoked early in the boot sequence after the > * hypervisor has been detected. > @@ -426,6 +448,11 @@ 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();Another place where the EBX value saved into the ms_hyperv structure could be used.> + > + BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull); > + > return; > > remove_cpuhp_state: > diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h > index 62d9390f1ddf..67f5d35a73d3 100644 > --- a/arch/x86/include/asm/mshyperv.h > +++ b/arch/x86/include/asm/mshyperv.h > @@ -78,6 +78,8 @@ extern void *hv_hypercall_pg; > extern void __percpu **hyperv_pcpu_input_arg; > extern void __percpu **hyperv_pcpu_output_arg; > > +extern u64 hv_current_partition_id; > + > static inline u64 hv_do_hypercall(u64 control, void *input, void *output) > { > u64 input_address = input ? virt_to_phys(input) : 0; > diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h > index e6903589a82a..87b1a79b19eb 100644 > --- a/include/asm-generic/hyperv-tlfs.h > +++ b/include/asm-generic/hyperv-tlfs.h > @@ -141,6 +141,7 @@ struct ms_hyperv_tsc_page { > #define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX 0x0013 > #define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX 0x0014 > #define HVCALL_SEND_IPI_EX 0x0015 > +#define HVCALL_GET_PARTITION_ID 0x0046 > #define HVCALL_GET_VP_REGISTERS 0x0050 > #define HVCALL_SET_VP_REGISTERS 0x0051 > #define HVCALL_POST_MESSAGE 0x005c > @@ -407,6 +408,11 @@ struct hv_tlb_flush_ex { > u64 gva_list[]; > } __packed; > > +/* HvGetPartitionId hypercall (output only) */ > +struct hv_get_partition_id { > + u64 partition_id; > +} __packed; > + > /* HvRetargetDeviceInterrupt hypercall */ > union hv_msi_entry { > u64 as_uint64; > -- > 2.20.1