From: "Arnd Bergmann" <arnd@arndb.de>
To: "Roman Kisel" <romank@linux.microsoft.com>
Cc: benhill@microsoft.com, bperkins@microsoft.com,
sunilmut@microsoft.com, bhelgaas@google.com,
"Borislav Petkov" <bp@alien8.de>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Conor Dooley" <conor+dt@kernel.org>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Dexuan Cui" <decui@microsoft.com>,
"Haiyang Zhang" <haiyangz@microsoft.com>,
"H. Peter Anvin" <hpa@zytor.com>,
krzk+dt@kernel.org, "Krzysztof Wilczyński" <kw@linux.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
"Manivannan Sadhasivam" <manivannan.sadhasivam@linaro.org>,
"Ingo Molnar" <mingo@redhat.com>, "Rob Herring" <robh@kernel.org>,
ssengar@linux.microsoft.com,
"Thomas Gleixner" <tglx@linutronix.de>,
"Wei Liu" <wei.liu@kernel.org>, "Will Deacon" <will@kernel.org>,
devicetree@vger.kernel.org,
Linux-Arch <linux-arch@vger.kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-pci@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH hyperv-next v4 1/6] arm64: hyperv: Use SMCCC to detect hypervisor presence
Date: Tue, 25 Feb 2025 08:24:51 +0100 [thread overview]
Message-ID: <55b65ba6-4abe-478c-a173-4622c30ddd7b@app.fastmail.com> (raw)
In-Reply-To: <14a199d8-1cf3-49bc-8e0d-92d9c8407b4f@linux.microsoft.com>
On Tue, Feb 25, 2025, at 00:22, Roman Kisel wrote:
> Hi Arnd,
>
> [...]
>
>>> I would suggest moving the UUID values into a variable next
>>> to the caller like
>>>
>>> #define ARM_SMCCC_VENDOR_HYP_UID_KVM \
>>> UUID_INIT(0x28b46fb6, 0x2ec5, 0x11e9, 0xa9, 0xca, 0x4b, 0x56,
>>> 0x4d, 0x00, 0x3a, 0x74)
>>>
>>> and then just pass that into arm_smccc_hyp_present(). (please
>>> double-check the endianess of the definition here, I probably
>>> got it wrong myself).
>
> I worked out a variation [1] of the change that you said looked good.
>
> Here, there is a helper macro for creating uuid_t's when checking
> for the hypervisor running via SMCCC to avoid using the bare UUID_INIT.
> Valiadted with KVM/arm64 and Hyper-V/arm64. Do you think this is a
> better approach than converting by hand?
>
> If that looks too heavy, maybe could leave out converting the expected
> register values to UUID, and pass the expected register values to
> arm_smccc_hyp_present directly. That way, instead of
>
> bool arm_smccc_hyp_present(const uuid_t *hyp_uuid);
>
> we'd have
>
> bool arm_smccc_hyp_present(u32 reg0, u32 reg1, u32 reg2, u32 reg2);
>
>
> Please let me know what you think!
The patch looks correct to me, but I agree it's a little silly
to convert register values into uuid format on both sides.
> static bool hyperv_detect_via_smccc(void)
> {
> - struct arm_smccc_res res = {};
> + uuid_t hyperv_uuid = HYP_UUID_INIT(ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_0,
> + ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_1,
> + ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_2,
> + ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_3);
If you want to declare a uuid here, I think you should remove the
ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_{0,1,2,3} macros and just
have UUID in normal UUID_INIT() notation as we do for
other UUIDs.
If you want to keep the four 32-bit values and pass them into
arm_smccc_hyp_present() directly, I think that is also fine,
but in that case, I would try to avoid calling it a UUID.
How are the kvm and hyperv values specified originally?
From the SMCCC document it seems like they are meant to be
UUIDs, so I would expect them to be in canonical form rather
than the smccc return values, but I could not find a document
for them.
Arnd
next prev parent reply other threads:[~2025-02-25 7:25 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 [this message]
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
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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