linux-kernel - RE: [PATCH v5] x86/Hyper-V: Support for free page reporting

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Message-ID: <MWHPR21MB1593992852105271128FF8C6D7649@MWHPR21MB1593.namprd21.prod.outlook.com>
Date:   Tue, 23 Mar 2021 18:53:47 +0000
From:   Michael Kelley <mikelley@...rosoft.com>
To:     Sunil Muthuswamy <sunilmut@...rosoft.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <liuwe@...rosoft.com>,
        Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, vkuznets <vkuznets@...hat.com>
CC:     KY Srinivasan <kys@...rosoft.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Matheus Castello <matheus@...tello.eng.br>
Subject: RE: [PATCH v5] x86/Hyper-V: Support for free page reporting

From: Sunil Muthuswamy <sunilmut@...rosoft.com> Sent: Tuesday, March 23, 2021 11:47 AM
> 
> Linux has support for free page reporting now (36e66c554b5c) for
> virtualized environment. On Hyper-V when virtually backed VMs are
> configured, Hyper-V will advertise cold memory discard capability,
> when supported. This patch adds the support to hook into the free
> page reporting infrastructure and leverage the Hyper-V cold memory
> discard hint hypercall to report/free these pages back to the host.
> 
> Signed-off-by: Sunil Muthuswamy <sunilmut@...rosoft.com>
> Tested-by: Matheus Castello <matheus@...tello.eng.br>
> ---
> In V2:
> - Addressed feedback comments
> - Added page reporting config option tied to hyper-v balloon config
> 
> In V3:
> - Addressed feedback from Vitaly
> 
> In V4:
> - Queried and cached the Hyper-V extended capability for the lifetime
>   of the VM
> - Addressed feedback from Michael Kelley.
> 
> In v5:
> - Added a comment clarifying handling of failed query extended
>   capability hypercall to address Michael's feedback.
> ---
>  arch/x86/hyperv/hv_init.c         | 51 +++++++++++++++++-
>  arch/x86/kernel/cpu/mshyperv.c    |  9 ++--
>  drivers/hv/Kconfig                |  1 +
>  drivers/hv/hv_balloon.c           | 89 +++++++++++++++++++++++++++++++
>  include/asm-generic/hyperv-tlfs.h | 35 +++++++++++-
>  include/asm-generic/mshyperv.h    |  3 +-
>  6 files changed, 180 insertions(+), 8 deletions(-)
> 

Reviewed-by:  Michael Kelley <mikelley@...rosoft.com>