From: Wei Liu <wei.liu@kernel.org>
To: Michael Kelley <mikelley@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>,
Linux on Hyper-V List <linux-hyperv@vger.kernel.org>,
"virtualization@lists.linux-foundation.org"
<virtualization@lists.linux-foundation.org>,
Linux Kernel List <linux-kernel@vger.kernel.org>,
Vineeth Pillai <viremana@linux.microsoft.com>,
Sunil Muthuswamy <sunilmut@microsoft.com>,
Nuno Das Neves <nunodasneves@linux.microsoft.com>,
"pasha.tatashin@soleen.com" <pasha.tatashin@soleen.com>,
KY 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>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v5 02/16] x86/hyperv: detect if Linux is the root partition
Date: Tue, 26 Jan 2021 15:15:12 +0000 [thread overview]
Message-ID: <20210126151512.jz4f3jxfs7ommvm3@liuwe-devbox-debian-v2> (raw)
In-Reply-To: <MWHPR21MB159358B1D6151AC5B5D38C7FD7BC9@MWHPR21MB1593.namprd21.prod.outlook.com>
On Tue, Jan 26, 2021 at 12:31:31AM +0000, Michael Kelley wrote:
> From: Wei Liu <wei.liu@kernel.org> Sent: Wednesday, January 20, 2021 4:01 AM
> >
> > 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>
> > ---
> > v3: move hv_root_partition to mshyperv.c
> > ---
> > arch/x86/include/asm/hyperv-tlfs.h | 10 ++++++++++
> > arch/x86/include/asm/mshyperv.h | 2 ++
> > arch/x86/kernel/cpu/mshyperv.c | 20 ++++++++++++++++++++
> > 3 files changed, 32 insertions(+)
> >
> > diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> > index 6bf42aed387e..204010350604 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_CPUID_VIRT_STACK_INTERFACE 0x40000081
> > @@ -110,6 +111,15 @@
> > /* 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)
> > +
>
> I wonder if these bit definitions should go in the asm-generic part of
> hyperv-tlfs.h instead of the X64 specific part. They look very architecture
> neutral (in which case the X64 should be dropped from the name
> as well). Of course, they can be moved later when/if we get to that point
> and have a firmer understanding of what is and isn't arch neutral.
Yes. This is the approach I'm taking here. They can be easily moved in
the future if there is a need.
>
> > /*
> > * 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 f628e3dc150f..c376d191a260 100644
> > --- a/arch/x86/kernel/cpu/mshyperv.c
> > +++ b/arch/x86/kernel/cpu/mshyperv.c
> > @@ -32,6 +32,10 @@
> > #include <asm/nmi.h>
> > #include <clocksource/hyperv_timer.h>
> >
> > +/* Is Linux running as the root partition? */
> > +bool hv_root_partition;
> > +EXPORT_SYMBOL_GPL(hv_root_partition);
> > +
> > struct ms_hyperv_info ms_hyperv;
> > EXPORT_SYMBOL_GPL(ms_hyperv);
> >
> > @@ -237,6 +241,22 @@ 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) {
>
> Should the EBX value be captured in the ms_hyperv structure with the
> other similar values, and then used from there?
>
There is only one usage of this in this whole series so I didn't bother
capturing. I would also like to clean up ms_hyperv_info's fields a bit.
Given there are quite some patches pending which change ms_hyperv_info
struct, I would like to avoid creating more conflicts than necessary.
My plan is to implement my idea from the thread "Field names inside
ms_hyperv_info" once all patches that touch ms_hyperv_info are merged.
Wei.
next prev parent reply other threads:[~2021-01-26 15:17 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-20 12:00 [PATCH v5 00/16] Introducing Linux root partition support for Microsoft Hypervisor Wei Liu
2021-01-20 12:00 ` [PATCH v5 01/16] asm-generic/hyperv: change HV_CPU_POWER_MANAGEMENT to HV_CPU_MANAGEMENT Wei Liu
2021-01-20 15:57 ` Pavel Tatashin
2021-01-26 0:25 ` Michael Kelley
2021-01-20 12:00 ` [PATCH v5 02/16] x86/hyperv: detect if Linux is the root partition Wei Liu
2021-01-20 16:03 ` Pavel Tatashin
2021-01-26 15:06 ` Wei Liu
2021-01-26 0:31 ` Michael Kelley
2021-01-26 15:15 ` Wei Liu [this message]
2021-01-26 15:24 ` Wei Liu
2021-01-20 12:00 ` [PATCH v5 03/16] Drivers: hv: vmbus: skip VMBus initialization if Linux is root Wei Liu
2021-01-20 16:06 ` Pavel Tatashin
2021-01-26 0:32 ` Michael Kelley
2021-01-20 12:00 ` [PATCH v5 04/16] iommu/hyperv: don't setup IRQ remapping when running as root Wei Liu
2021-01-20 16:08 ` Pavel Tatashin
2021-01-26 0:33 ` Michael Kelley
2021-01-20 12:00 ` [PATCH v5 05/16] clocksource/hyperv: use MSR-based access if " Wei Liu
2021-01-20 16:13 ` Pavel Tatashin
2021-01-26 15:19 ` Wei Liu
2021-01-26 0:34 ` Michael Kelley
2021-01-20 12:00 ` [PATCH v5 06/16] x86/hyperv: allocate output arg pages if required Wei Liu
2021-01-20 15:12 ` kernel test robot
2021-01-20 19:44 ` Pavel Tatashin
2021-01-26 0:41 ` Michael Kelley
2021-01-26 18:09 ` Wei Liu
2021-01-20 12:00 ` [PATCH v5 07/16] x86/hyperv: extract partition ID from Microsoft Hypervisor if necessary Wei Liu
2021-01-26 0:48 ` Michael Kelley
2021-02-02 15:03 ` Wei Liu
2021-02-04 16:33 ` Michael Kelley
2021-01-20 12:00 ` [PATCH v5 08/16] x86/hyperv: handling hypercall page setup for root Wei Liu
2021-01-26 0:49 ` Michael Kelley
2021-01-20 12:00 ` [PATCH v5 09/16] x86/hyperv: provide a bunch of helper functions Wei Liu
2021-01-26 1:20 ` Michael Kelley
2021-02-02 16:19 ` Wei Liu
2021-01-20 12:00 ` [PATCH v5 10/16] x86/hyperv: implement and use hv_smp_prepare_cpus Wei Liu
2021-01-26 1:21 ` Michael Kelley
2021-01-20 12:00 ` [PATCH v5 11/16] asm-generic/hyperv: update hv_msi_entry Wei Liu
2021-01-26 1:22 ` Michael Kelley
2021-01-20 12:00 ` [PATCH v5 12/16] asm-generic/hyperv: update hv_interrupt_entry Wei Liu
2021-01-26 1:23 ` Michael Kelley
2021-01-20 12:00 ` [PATCH v5 13/16] asm-generic/hyperv: introduce hv_device_id and auxiliary structures Wei Liu
2021-01-26 1:26 ` Michael Kelley
2021-02-02 17:02 ` Wei Liu
2021-02-03 13:26 ` Wei Liu
2021-02-03 13:49 ` Arnd Bergmann
2021-02-03 14:09 ` Wei Liu
2021-02-04 16:46 ` Michael Kelley
2021-01-20 12:00 ` [PATCH v5 14/16] asm-generic/hyperv: import data structures for mapping device interrupts Wei Liu
2021-01-26 1:27 ` Michael Kelley
2021-01-20 12:00 ` [PATCH v5 15/16] x86/hyperv: implement an MSI domain for root partition Wei Liu
2021-01-27 5:47 ` Michael Kelley
2021-02-02 17:31 ` Wei Liu
2021-02-02 18:15 ` Michael Kelley
2021-02-02 18:16 ` Wei Liu
2021-01-20 12:00 ` [PATCH v5 16/16] iommu/hyperv: setup an IO-APIC IRQ remapping " Wei Liu
2021-01-27 5:47 ` Michael Kelley
2021-02-03 12:47 ` Wei Liu
2021-02-04 16:41 ` Michael Kelley
2021-02-04 16:48 ` Wei Liu
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