From: Michael Kelley <mikelley@microsoft.com>
To: vkuznets <vkuznets@redhat.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
Stephen Hemminger <sthemmin@microsoft.com>,
KY Srinivasan <kys@microsoft.com>,
"wei.liu@kernel.org" <wei.liu@kernel.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"bp@alien8.de" <bp@alien8.de>, "hpa@zytor.com" <hpa@zytor.com>,
"daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>,
"arnd@arndb.de" <arnd@arndb.de>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>
Subject: RE: ** POTENTIAL FRAUD ALERT - RED HAT ** [PATCH v2 01/10] Drivers: hv: vmbus: Move Hyper-V page allocator to arch neutral code
Date: Tue, 2 Mar 2021 17:42:30 +0000 [thread overview]
Message-ID: <MWHPR21MB1593AE5172A203C3D62B8C06D7999@MWHPR21MB1593.namprd21.prod.outlook.com> (raw)
In-Reply-To: <87r1kxemsj.fsf@vitty.brq.redhat.com>
From: Vitaly Kuznetsov <vkuznets@redhat.com> Sent: Tuesday, March 2, 2021 4:57 AM
>
> Michael Kelley <mikelley@microsoft.com> writes:
>
> > The Hyper-V page allocator functions are implemented in an architecture
> > neutral way. Move them into the architecture neutral VMbus module so
> > a separate implementation for ARM64 is not needed.
> >
> > No functional change.
> >
> > Signed-off-by: Michael Kelley <mikelley@microsoft.com>
> > Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
> > ---
> > arch/x86/hyperv/hv_init.c | 22 ----------------------
> > arch/x86/include/asm/mshyperv.h | 5 -----
> > drivers/hv/hv.c | 36 ++++++++++++++++++++++++++++++++++++
> > include/asm-generic/mshyperv.h | 4 ++++
> > 4 files changed, 40 insertions(+), 27 deletions(-)
> >
[snip]
> >
> > /*
> > + * Functions for allocating and freeing memory with size and
> > + * alignment HV_HYP_PAGE_SIZE. These functions are needed because
> > + * the guest page size may not be the same as the Hyper-V page
> > + * size. We depend upon kmalloc() aligning power-of-two size
> > + * allocations to the allocation size boundary, so that the
> > + * allocated memory appears to Hyper-V as a page of the size
> > + * it expects.
> > + */
> > +
> > +void *hv_alloc_hyperv_page(void)
> > +{
> > + BUILD_BUG_ON(PAGE_SIZE < HV_HYP_PAGE_SIZE);
> > +
> > + if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
> > + return (void *)__get_free_page(GFP_KERNEL);
> > + else
> > + return kmalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
>
> PAGE_SIZE and HV_HYP_PAGE_SIZE are known compile-time and in case this
> won't change in the future we can probably write this as
>
> #if PAGE_SIZE == HV_HYP_PAGE_SIZE
> return (void *)__get_free_page(GFP_KERNEL);
> #else
> return kmalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
> #endif
>
> (not sure if the output is going to be any different with e.g. gcc's '-O2')
>
I looked at the generated code, and the compiler does the right
thing on both x86/x64 and on ARM64. I'd rather leave the code
as is so that both legs of the 'if' statement get checked by the
compiler regardless of whether PAGE_SIZE == HV_HYP_PAGE_SIZE.
Michael
> > +}
> > +
> > +void *hv_alloc_hyperv_zeroed_page(void)
> > +{
> > + if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
> > + return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
> > + else
> > + return kzalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
> > +}
> > +
> > +void hv_free_hyperv_page(unsigned long addr)
> > +{
> > + if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
> > + free_page(addr);
> > + else
> > + kfree((void *)addr);
> > +}
> > +
> > +/*
next prev parent reply other threads:[~2021-03-03 5:38 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-01 1:15 [PATCH v2 00/10] Refactor arch specific Hyper-V code Michael Kelley
2021-03-01 1:15 ` [PATCH v2 01/10] Drivers: hv: vmbus: Move Hyper-V page allocator to arch neutral code Michael Kelley
2021-03-02 12:57 ` ** POTENTIAL FRAUD ALERT - RED HAT ** " Vitaly Kuznetsov
2021-03-02 17:42 ` Michael Kelley [this message]
2021-03-01 1:15 ` [PATCH v2 02/10] x86/hyper-v: Move hv_message_type to architecture neutral module Michael Kelley
2021-03-01 1:15 ` [PATCH v2 03/10] Drivers: hv: Redo Hyper-V synthetic MSR get/set functions Michael Kelley
2021-03-01 1:15 ` [PATCH v2 04/10] Drivers: hv: vmbus: Move hyperv_report_panic_msg to arch neutral code Michael Kelley
2021-03-01 1:15 ` [PATCH v2 05/10] Drivers: hv: vmbus: Handle auto EOI quirk inline Michael Kelley
2021-03-01 1:15 ` [PATCH v2 06/10] Drivers: hv: vmbus: Move handling of VMbus interrupts Michael Kelley
2021-03-01 1:15 ` [PATCH v2 07/10] clocksource/drivers/hyper-v: Handle vDSO differences inline Michael Kelley
2021-03-01 12:21 ` Daniel Lezcano
2021-03-02 1:29 ` Michael Kelley
2021-03-02 13:01 ` Daniel Lezcano
2021-03-01 1:15 ` [PATCH v2 08/10] clocksource/drivers/hyper-v: Handle sched_clock " Michael Kelley
2021-03-01 14:25 ` Daniel Lezcano
2021-03-02 1:38 ` Michael Kelley
2021-03-02 13:34 ` Daniel Lezcano
2021-03-01 1:15 ` [PATCH v2 09/10] clocksource/drivers/hyper-v: Set clocksource rating based on Hyper-V feature Michael Kelley
2021-03-01 15:42 ` Daniel Lezcano
2021-03-01 1:15 ` [PATCH v2 10/10] clocksource/drivers/hyper-v: Move handling of STIMER0 interrupts Michael Kelley
2021-03-01 18:44 ` Daniel Lezcano
2021-03-02 1:40 ` Michael Kelley
2021-03-01 11:30 ` [PATCH v2 00/10] Refactor arch specific Hyper-V code Wei Liu
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