Re: [PATCH RFC v1 07/18] x86/hyperv: extract partition ID from Microsoft Hypervisor if necessary
From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: 2020-09-15 10:27:35
Also in:
linux-arch, lkml, virtualization
Wei Liu [off-list ref] writes:
quoted hunk ↗ jump to hunk
We will need the partition ID for executing some hypercalls later. Signed-off-by: Lillian Grassin-Drake <redacted> Co-Developed-by: Sunil Muthuswamy <redacted> Signed-off-by: Wei Liu <wei.liu@kernel.org> --- arch/x86/hyperv/hv_init.c | 26 ++++++++++++++++++++++++++ arch/x86/include/asm/mshyperv.h | 2 ++ include/asm-generic/hyperv-tlfs.h | 6 ++++++ 3 files changed, 34 insertions(+)diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index ebba4be4185d..0eec1ed32023 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c@@ -30,6 +30,9 @@ bool hv_root_partition; EXPORT_SYMBOL_GPL(hv_root_partition); +u64 hv_current_partition_id; +EXPORT_SYMBOL_GPL(hv_current_partition_id); + void *hv_hypercall_pg; EXPORT_SYMBOL_GPL(hv_hypercall_pg);@@ -345,6 +348,26 @@ static struct syscore_ops hv_syscore_ops = { .resume = hv_resume, }; +void __init hv_get_partition_id(void) +{ + struct hv_get_partition_id *output_page; + int 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;
Nit: in this case status is 'u16', we can define it as such (instead of signed int).
quoted hunk ↗ jump to hunk
+ if (status != HV_STATUS_SUCCESS) + pr_err("Failed to get partition ID: %d\n", status); + else + hv_current_partition_id = output_page->partition_id; + local_irq_restore(flags); + + /* No point in proceeding if this failed */ + BUG_ON(status != HV_STATUS_SUCCESS); +} + /* * This function is to be invoked early in the boot sequence after the * hypervisor has been detected.@@ -440,6 +463,9 @@ void __init hyperv_init(void) register_syscore_ops(&hv_syscore_ops); + if (hv_root_partition) + hv_get_partition_id();
According to TLFS, partition ID is available when AccessPartitionId
privilege is granted. I'd suggest we check that instead of
hv_root_partition (and we can set hv_current_partition_id to something
like U64_MAX so we know it wasn't acuired). So the BUG_ON condition will
move here:
hv_get_partition_id();
BUG_ON(hv_root_partition && hv_current_partition_id == U64_MAX);
quoted hunk ↗ jump to hunk
+ return; remove_cpuhp_state:diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h index f5c62140f28d..4039302e0ae9 100644 --- a/arch/x86/include/asm/mshyperv.h +++ b/arch/x86/include/asm/mshyperv.h@@ -65,6 +65,8 @@ 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;
-- Vitaly