From: Roman Kisel <romank@linux.microsoft.com>
To: Michael Kelley <mhklinux@outlook.com>,
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Cc: "benhill@microsoft.com" <benhill@microsoft.com>,
"bperkins@microsoft.com" <bperkins@microsoft.com>,
"sunilmut@microsoft.com" <sunilmut@microsoft.com>
Subject: Re: [PATCH hyperv-next v4 1/6] arm64: hyperv: Use SMCCC to detect hypervisor presence
Date: Thu, 20 Feb 2025 08:34:59 -0800 [thread overview]
Message-ID: <fa2d9e8d-7897-44eb-87e2-3a9118deb18a@linux.microsoft.com> (raw)
In-Reply-To: <SN6PR02MB4157DB2F52501309D52D0870D4C52@SN6PR02MB4157.namprd02.prod.outlook.com>
On 2/19/2025 3:13 PM, Michael Kelley wrote:
> From: Roman Kisel <romank@linux.microsoft.com> Sent: Tuesday, February 11, 2025 5:43 PM
>>
[...]
>> }
>>
>> +static bool hyperv_detect_via_acpi(void)
>> +{
>> + if (acpi_disabled)
>> + return false;
>> +#if IS_ENABLED(CONFIG_ACPI)
>> + /* Hypervisor ID is only available in ACPI v6+. */
>
> The comment is correct, but to me doesn't tell the full story.
> I initially wondered why the revision test < 6 was being done,
> since Hyper-V for ARM64 always provides ACPI 6.x or greater.
> But the test is needed to catch running in some unknown
> non-Hyper-V environment that has ACPI 5.x or less. In such a
> case, it can't be Hyper-V, so just return false instead of testing
> a bogus hypervisor_id field. Maybe a comment would help
> explain it to someone like me who was confused. :-)
>
Thanks, I'll extend the comment to tell the whole story!
[...]
>> + ms_hyperv.vtl = get_vtl();
>
> The above statement looks like it will fail to compile on
> arm64 since the get_vtl() function is entirely on the x86
> side until Patch 3 of this series. As of this Patch 1, there's
> no declaration of get_vtl() available to arm64.
>
I used my working branch for testing
https://github.com/romank-msft/linux-hyperv/tree/vtl_mode_arm64_v4
and didn't move that code around when chunking into patches.
Will fix the workflow, thanks for catching this!
>> + /* Report if non-default VTL */
>> + if (ms_hyperv.vtl > 0)
>> + pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
>
> Could this message include the VTL number as well? In the long
> run, I think there will be code at non-zero VTLs other than VTL 2.
>
Absolutely, will add!
>> +
>> ms_hyperv_late_init();
>>
>> hyperv_initialized = true;
>> diff --git a/arch/arm64/include/asm/mshyperv.h
>> b/arch/arm64/include/asm/mshyperv.h
>> index 2e2f83bafcfb..a6d7eb9e167b 100644
>> --- a/arch/arm64/include/asm/mshyperv.h
>> +++ b/arch/arm64/include/asm/mshyperv.h
>> @@ -50,4 +50,9 @@ static inline u64 hv_get_msr(unsigned int reg)
>>
>> #include <asm-generic/mshyperv.h>
>>
>> +#define ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_0 0x4d32ba58U
>> +#define ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_1 0xcd244764U
>> +#define ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_2 0x8eef6c75U
>> +#define ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_3 0x16597024U
>> +
>> #endif
>> --
>> 2.43.0
>>
--
Thank you,
Roman
next prev parent reply other threads:[~2025-02-20 16:35 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-12 1:43 [PATCH hyperv-next v4 0/6] arm64: hyperv: Support Virtual Trust Level Boot Roman Kisel
2025-02-12 1:43 ` [PATCH hyperv-next v4 1/6] arm64: hyperv: Use SMCCC to detect hypervisor presence Roman Kisel
2025-02-12 6:54 ` Arnd Bergmann
2025-02-13 23:23 ` Roman Kisel
2025-02-14 8:05 ` Arnd Bergmann
2025-02-14 16:47 ` Roman Kisel
2025-02-24 23:22 ` Roman Kisel
2025-02-25 7:24 ` Arnd Bergmann
2025-02-25 22:25 ` Roman Kisel
2025-02-26 13:57 ` Arnd Bergmann
2025-02-19 23:13 ` Michael Kelley
2025-02-20 16:34 ` Roman Kisel [this message]
2025-02-12 1:43 ` [PATCH hyperv-next v4 2/6] Drivers: hv: Enable VTL mode for arm64 Roman Kisel
2025-02-19 23:14 ` Michael Kelley
2025-02-20 16:36 ` Roman Kisel
2025-02-12 1:43 ` [PATCH hyperv-next v4 3/6] Drivers: hv: Provide arch-neutral implementation of get_vtl() Roman Kisel
2025-02-19 23:17 ` Michael Kelley
2025-02-12 1:43 ` [PATCH hyperv-next v4 4/6] dt-bindings: microsoft,vmbus: Add GIC and DMA coherence to the example Roman Kisel
2025-02-12 6:42 ` Krzysztof Kozlowski
2025-02-12 23:57 ` Roman Kisel
2025-02-13 20:50 ` Roman Kisel
2025-02-12 1:43 ` [PATCH hyperv-next v4 5/6] Drivers: hv: vmbus: Get the IRQ number from DeviceTree Roman Kisel
2025-02-19 23:20 ` Michael Kelley
2025-02-12 1:43 ` [PATCH hyperv-next v4 6/6] PCI: hv: Get vPCI MSI IRQ domain " Roman Kisel
2025-02-12 17:42 ` Bjorn Helgaas
2025-02-18 22:32 ` Roman Kisel
2025-02-19 23:51 ` Roman Kisel
2025-02-19 23:29 ` Michael Kelley
2025-02-20 16:41 ` Roman Kisel
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