From: Mark Rutland <mark.rutland@arm.com>
To: Michael Kelley <mikelley@microsoft.com>
Cc: "will@kernel.org" <will@kernel.org>,
"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
"lorenzo.pieralisi@arm.com" <lorenzo.pieralisi@arm.com>,
"sudeep.holla@arm.com" <sudeep.holla@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
"arnd@arndb.de" <arnd@arndb.de>,
"wei.liu@kernel.org" <wei.liu@kernel.org>,
"ardb@kernel.org" <ardb@kernel.org>,
"daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>,
KY Srinivasan <kys@microsoft.com>
Subject: Re: [PATCH v10 2/7] arm64: hyperv: Add Hyper-V hypercall and register access utilities
Date: Mon, 17 May 2021 12:44:49 +0100 [thread overview]
Message-ID: <20210517114449.GB62656@C02TD0UTHF1T.local> (raw)
In-Reply-To: <MWHPR21MB1593A7625285A3E3F376B352D7509@MWHPR21MB1593.namprd21.prod.outlook.com>
On Fri, May 14, 2021 at 03:14:41PM +0000, Michael Kelley wrote:
> From: Mark Rutland <mark.rutland@arm.com> Sent: Friday, May 14, 2021 5:53 AM
> >
> > On Wed, May 12, 2021 at 10:37:42AM -0700, Michael Kelley wrote:
> > > hyperv-tlfs.h defines Hyper-V interfaces from the Hyper-V Top Level
> > > Functional Spec (TLFS), and #includes the architecture-independent
> > > part of hyperv-tlfs.h in include/asm-generic. The published TLFS
> > > is distinctly oriented to x86/x64, so the ARM64-specific
> > > hyperv-tlfs.h includes information for ARM64 that is not yet formally
> > > published. The TLFS is available here:
> > >
> > > docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs
> > >
> > > mshyperv.h defines Linux-specific structures and routines for
> > > interacting with Hyper-V on ARM64, and #includes the architecture-
> > > independent part of mshyperv.h in include/asm-generic.
> > >
> > > Use these definitions to provide utility functions to make
> > > Hyper-V hypercalls and to get and set Hyper-V provided
> > > registers associated with a virtual processor.
> > >
> > > Signed-off-by: Michael Kelley <mikelley@microsoft.com>
> > > Reviewed-by: Sunil Muthuswamy <sunilmut@microsoft.com>
> > > ---
> > > MAINTAINERS | 3 +
> > > arch/arm64/Kbuild | 1 +
> > > arch/arm64/hyperv/Makefile | 2 +
> > > arch/arm64/hyperv/hv_core.c | 130 +++++++++++++++++++++++++++++++++++
> > > arch/arm64/include/asm/hyperv-tlfs.h | 69 +++++++++++++++++++
> > > arch/arm64/include/asm/mshyperv.h | 54 +++++++++++++++
> > > 6 files changed, 259 insertions(+)
> > > create mode 100644 arch/arm64/hyperv/Makefile
> > > create mode 100644 arch/arm64/hyperv/hv_core.c
> > > create mode 100644 arch/arm64/include/asm/hyperv-tlfs.h
> > > create mode 100644 arch/arm64/include/asm/mshyperv.h
> >
> > > +/*
> > > + * hv_do_hypercall- Invoke the specified hypercall
> > > + */
> > > +u64 hv_do_hypercall(u64 control, void *input, void *output)
> > > +{
> > > + struct arm_smccc_res res;
> > > + u64 input_address;
> > > + u64 output_address;
> > > +
> > > + input_address = input ? virt_to_phys(input) : 0;
> > > + output_address = output ? virt_to_phys(output) : 0;
> >
> > I may have asked this before, but are `input` and `output` always linear
> > map pointers, or can they ever be vmalloc pointers?
> >
> > Otherwise, this looks fine to me.
>
> The caller must ensure that hypercall arguments are aligned to
> 4 Kbytes, and no larger than 4 Kbytes, since that's the page size
> used by Hyper-V regardless of the guest page size. A per-CPU
> 4 Kbyte memory area (hyperv_pcpu_input_arg) meeting these
> requirements is pre-allocated that callers can use for this purpose.
What I was trying to find out was how that was allocated, as vmalloc()'d
pointers aren't legitimate to pass to virt_to_phys().
From scanning ahead to patch 5, I see that memory comes from kmalloc(),
and so it is legitimate to use virt_to_phys().
I see; and from patch 5 I see that memory come from kmalloc(), and will
therefore be part of the linear map, and so virt_to_phys() is
legitimate.
What I was asking here was how that memory was allocated. So long as
those are the only buffers used, this looks fine to me.
Thanks,
Mark.
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next prev parent reply other threads:[~2021-05-17 11:46 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-12 17:37 [PATCH v10 0/7] Enable Linux guests on Hyper-V on ARM64 Michael Kelley
2021-05-12 17:37 ` [PATCH v10 1/7] asm-generic: hyperv: Fix incorrect architecture dependencies Michael Kelley
2021-05-12 17:37 ` [PATCH v10 2/7] arm64: hyperv: Add Hyper-V hypercall and register access utilities Michael Kelley
2021-05-14 12:52 ` Mark Rutland
2021-05-14 15:14 ` Michael Kelley
2021-05-17 11:44 ` Mark Rutland [this message]
2021-05-17 16:41 ` Michael Kelley
2021-05-12 17:37 ` [PATCH v10 3/7] arm64: hyperv: Add Hyper-V clocksource/clockevent support Michael Kelley
2021-05-14 12:37 ` Mark Rutland
2021-05-14 15:35 ` Michael Kelley
2021-05-17 13:08 ` Mark Rutland
2021-05-17 17:27 ` Michael Kelley
2021-05-18 17:00 ` Mark Rutland
2021-06-08 15:36 ` Michael Kelley
2021-06-10 16:45 ` Mark Rutland
2021-06-14 2:42 ` Michael Kelley
2021-06-16 20:17 ` Michael Kelley
2021-06-22 9:54 ` Mark Rutland
2021-06-23 8:56 ` Marc Zyngier
2021-06-28 2:21 ` Michael Kelley
2021-05-12 17:37 ` [PATCH v10 4/7] arm64: hyperv: Add kexec and panic handlers Michael Kelley
2021-05-12 17:37 ` [PATCH v10 5/7] arm64: hyperv: Initialize hypervisor on boot Michael Kelley
2021-05-13 15:16 ` Wei Liu
2021-05-12 17:37 ` [PATCH v10 6/7] arm64: efi: Export screen_info Michael Kelley
2021-05-12 17:37 ` [PATCH v10 7/7] Drivers: hv: Enable Hyper-V code to be built on ARM64 Michael Kelley
2021-05-13 13:17 ` [PATCH v10 0/7] Enable Linux guests on Hyper-V " Sudeep Holla
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