From: Wei Liu <wei.liu@kernel.org>
To: Linux on Hyper-V List <linux-hyperv@vger.kernel.org>
Cc: virtualization@lists.linux-foundation.org,
Linux Kernel List <linux-kernel@vger.kernel.org>,
Michael Kelley <mikelley@microsoft.com>,
Vineeth Pillai <viremana@linux.microsoft.com>,
Sunil Muthuswamy <sunilmut@microsoft.com>,
Nuno Das Neves <nunodasneves@linux.microsoft.com>,
Wei Liu <wei.liu@kernel.org>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
"H. Peter Anvin" <hpa@zytor.com>
Subject: [PATCH v2 02/17] x86/hyperv: detect if Linux is the root partition
Date: Thu, 5 Nov 2020 16:57:59 +0000 [thread overview]
Message-ID: <20201105165814.29233-3-wei.liu@kernel.org> (raw)
In-Reply-To: <20201105165814.29233-1-wei.liu@kernel.org>
For now we can use the privilege flag to check. Stash the value to be
used later.
Put in a bunch of defines for future use when we want to have more
fine-grained detection.
Signed-off-by: Wei Liu <wei.liu@kernel.org>
---
arch/x86/hyperv/hv_init.c | 4 ++++
arch/x86/include/asm/hyperv-tlfs.h | 10 ++++++++++
arch/x86/include/asm/mshyperv.h | 2 ++
arch/x86/kernel/cpu/mshyperv.c | 16 ++++++++++++++++
4 files changed, 32 insertions(+)
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index e04d90af4c27..533fe9e887f2 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -26,6 +26,10 @@
#include <linux/syscore_ops.h>
#include <clocksource/hyperv_timer.h>
+/* Is Linux running as the root partition? */
+bool hv_root_partition;
+EXPORT_SYMBOL_GPL(hv_root_partition);
+
void *hv_hypercall_pg;
EXPORT_SYMBOL_GPL(hv_hypercall_pg);
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 0ed20e8bba9e..41b628b9fb15 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -21,6 +21,7 @@
#define HYPERV_CPUID_FEATURES 0x40000003
#define HYPERV_CPUID_ENLIGHTMENT_INFO 0x40000004
#define HYPERV_CPUID_IMPLEMENT_LIMITS 0x40000005
+#define HYPERV_CPUID_CPU_MANAGEMENT_FEATURES 0x40000007
#define HYPERV_CPUID_NESTED_FEATURES 0x4000000A
#define HYPERV_HYPERVISOR_PRESENT_BIT 0x80000000
@@ -103,6 +104,15 @@
/* Recommend using enlightened VMCS */
#define HV_X64_ENLIGHTENED_VMCS_RECOMMENDED BIT(14)
+/*
+ * CPU management features identification.
+ * These are HYPERV_CPUID_CPU_MANAGEMENT_FEATURES.EAX bits.
+ */
+#define HV_X64_START_LOGICAL_PROCESSOR BIT(0)
+#define HV_X64_CREATE_ROOT_VIRTUAL_PROCESSOR BIT(1)
+#define HV_X64_PERFORMANCE_COUNTER_SYNC BIT(2)
+#define HV_X64_RESERVED_IDENTITY_BIT BIT(31)
+
/*
* Virtual processor will never share a physical core with another virtual
* processor, except for virtual processors that are reported as sibling SMT
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index ffc289992d1b..ac2b0d110f03 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -237,6 +237,8 @@ int hyperv_fill_flush_guest_mapping_list(
struct hv_guest_mapping_flush_list *flush,
u64 start_gfn, u64 end_gfn);
+extern bool hv_root_partition;
+
#ifdef CONFIG_X86_64
void hv_apic_init(void);
void __init hv_init_spinlocks(void);
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 05ef1f4550cb..f7633e1e4c82 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -237,6 +237,22 @@ static void __init ms_hyperv_init_platform(void)
pr_debug("Hyper-V: max %u virtual processors, %u logical processors\n",
ms_hyperv.max_vp_index, ms_hyperv.max_lp_index);
+ /*
+ * Check CPU management privilege.
+ *
+ * To mirror what Windows does we should extract CPU management
+ * features and use the ReservedIdentityBit to detect if Linux is the
+ * root partition. But that requires negotiating CPU management
+ * interface (a process to be finalized).
+ *
+ * For now, use the privilege flag as the indicator for running as
+ * root.
+ */
+ if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_CPU_MANAGEMENT) {
+ hv_root_partition = true;
+ pr_info("Hyper-V: running as root partition\n");
+ }
+
/*
* Extract host information.
*/
--
2.20.1
next prev parent reply other threads:[~2020-11-05 16:59 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-05 16:57 [PATCH v2 00/17] Introducing Linux root partition support for Microsoft Hypervisor Wei Liu
2020-11-05 16:57 ` [PATCH v2 01/17] asm-generic/hyperv: change HV_CPU_POWER_MANAGEMENT to HV_CPU_MANAGEMENT Wei Liu
2020-11-12 15:14 ` Vitaly Kuznetsov
2020-11-05 16:57 ` Wei Liu [this message]
2020-11-05 19:16 ` [PATCH v2 02/17] x86/hyperv: detect if Linux is the root partition kernel test robot
2020-11-12 11:42 ` Wei Liu
2020-11-12 11:46 ` Wei Liu
2020-11-12 12:22 ` Wei Liu
2020-11-05 20:23 ` kernel test robot
2020-11-12 15:16 ` Vitaly Kuznetsov
2020-11-12 15:51 ` Wei Liu
2020-11-05 16:58 ` [PATCH v2 03/17] Drivers: hv: vmbus: skip VMBus initialization if Linux is root Wei Liu
2020-11-12 15:24 ` Vitaly Kuznetsov
2020-11-13 14:51 ` Wei Liu
2020-11-05 16:58 ` [PATCH v2 04/17] iommu/hyperv: don't setup IRQ remapping when running as root Wei Liu
2020-11-12 15:27 ` Vitaly Kuznetsov
2020-11-13 14:53 ` Wei Liu
2020-11-05 16:58 ` [PATCH v2 05/17] clocksource/hyperv: use MSR-based access if " Wei Liu
2020-11-12 9:56 ` Daniel Lezcano
2020-11-12 11:24 ` Wei Liu
2020-11-12 11:40 ` Daniel Lezcano
2020-11-12 11:42 ` Wei Liu
2020-11-12 15:30 ` Vitaly Kuznetsov
2020-11-12 15:52 ` Wei Liu
2020-11-05 16:58 ` [PATCH v2 06/17] x86/hyperv: allocate output arg pages if required Wei Liu
2020-11-12 15:35 ` Vitaly Kuznetsov
2020-11-13 15:05 ` Wei Liu
2020-11-05 16:58 ` [PATCH v2 07/17] x86/hyperv: extract partition ID from Microsoft Hypervisor if necessary Wei Liu
2020-11-05 20:07 ` kernel test robot
2020-11-12 11:54 ` Wei Liu
2020-11-05 20:20 ` kernel test robot
2020-11-12 15:44 ` Vitaly Kuznetsov
2020-11-13 15:21 ` Wei Liu
2020-11-05 16:58 ` [PATCH v2 08/17] x86/hyperv: handling hypercall page setup for root Wei Liu
2020-11-12 15:51 ` Vitaly Kuznetsov
2020-11-13 15:33 ` Wei Liu
2020-11-13 16:09 ` Wei Liu
2020-11-13 16:16 ` Vitaly Kuznetsov
2020-11-05 16:58 ` [PATCH v2 09/17] x86/hyperv: provide a bunch of helper functions Wei Liu
2020-11-12 15:57 ` Vitaly Kuznetsov
2020-11-13 15:51 ` Wei Liu
2020-11-13 16:13 ` Vitaly Kuznetsov
2020-11-16 11:41 ` Wei Liu
2020-11-05 16:58 ` [PATCH v2 10/17] x86/hyperv: implement and use hv_smp_prepare_cpus Wei Liu
2020-11-12 16:44 ` Vitaly Kuznetsov
2020-11-13 15:56 ` Wei Liu
2020-11-05 16:58 ` [PATCH v2 11/17] asm-generic/hyperv: update hv_msi_entry Wei Liu
2020-11-05 16:58 ` [PATCH v2 12/17] asm-generic/hyperv: update hv_interrupt_entry Wei Liu
2020-11-05 16:58 ` [PATCH v2 13/17] asm-generic/hyperv: introduce hv_device_id and auxiliary structures Wei Liu
2020-11-05 16:58 ` [PATCH v2 14/17] asm-generic/hyperv: import data structures for mapping device interrupts Wei Liu
2020-11-05 16:58 ` [PATCH v2 15/17] x86/hyperv: implement an MSI domain for root partition Wei Liu
2020-11-12 13:50 ` Wei Liu
2020-11-05 16:58 ` [PATCH v2 16/17] x86/ioapic: export a few functions and data structures via io_apic.h Wei Liu
2020-11-12 11:39 ` Wei Liu
2020-11-05 16:58 ` [PATCH v2 17/17] x86/hyperv: handle IO-APIC when running as root Wei Liu
2020-11-12 16:56 ` Vitaly Kuznetsov
2020-11-13 16:01 ` Wei Liu
2020-11-13 16:04 ` Wei Liu
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