From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Dexuan Cui <decui@microsoft.com>
Cc: "linux-arch\@vger.kernel.org" <linux-arch@vger.kernel.org>,
"arnd\@arndb.de" <arnd@arndb.de>, "bp\@alien8.de" <bp@alien8.de>,
"daniel.lezcano\@linaro.org" <daniel.lezcano@linaro.org>,
Haiyang Zhang <haiyangz@microsoft.com>,
"hpa\@zytor.com" <hpa@zytor.com>,
KY Srinivasan <kys@microsoft.com>,
"linux-hyperv\@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"mingo\@redhat.com" <mingo@redhat.com>,
"sashal\@kernel.org" <sashal@kernel.org>,
Stephen Hemminger <sthemmin@microsoft.com>,
"tglx\@linutronix.de" <tglx@linutronix.de>,
"x86\@kernel.org" <x86@kernel.org>,
Michael Kelley <mikelley@microsoft.com>,
Sasha Levin <Alexander.Levin@microsoft.com>
Subject: Re: [PATCH v5 1/3] x86/hyper-v: Suspend/resume the hypercall page for hibernation
Date: Thu, 26 Sep 2019 12:44:16 +0200 [thread overview]
Message-ID: <87ef0372wv.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <1567723581-29088-2-git-send-email-decui@microsoft.com>
Dexuan Cui <decui@microsoft.com> writes:
> This is needed for hibernation, e.g. when we resume the old kernel, we need
> to disable the "current" kernel's hypercall page and then resume the old
> kernel's.
>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> Reviewed-by: Michael Kelley <mikelley@microsoft.com>
> ---
> arch/x86/hyperv/hv_init.c | 33 +++++++++++++++++++++++++++++++++
> 1 file changed, 33 insertions(+)
>
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index 866dfb3..037b0f3 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -20,6 +20,7 @@
> #include <linux/hyperv.h>
> #include <linux/slab.h>
> #include <linux/cpuhotplug.h>
> +#include <linux/syscore_ops.h>
> #include <clocksource/hyperv_timer.h>
>
> void *hv_hypercall_pg;
> @@ -223,6 +224,34 @@ static int __init hv_pci_init(void)
> return 1;
> }
>
> +static int hv_suspend(void)
> +{
> + union hv_x64_msr_hypercall_contents hypercall_msr;
> +
> + /* Reset the hypercall page */
> + rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> + hypercall_msr.enable = 0;
> + wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> +
(trying to think out loud, not sure there's a real issue):
When PV IPIs (or PV TLB flush) are enabled we do the following checks:
if (!hv_hypercall_pg)
return false;
or
if (!hv_hypercall_pg)
goto do_native;
which will pass as we're not invalidating the pointer. Can we actually
be sure that the kernel will never try to send an IPI/do TLB flush
before we resume?
--
Vitaly
next prev parent reply other threads:[~2019-09-26 10:44 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-05 22:47 [PATCH v5 0/3] Enhance Hyper-V for hibernation Dexuan Cui
2019-09-05 22:47 ` [PATCH v5 1/3] x86/hyper-v: Suspend/resume the hypercall page " Dexuan Cui
2019-09-26 10:44 ` Vitaly Kuznetsov [this message]
2019-09-27 6:48 ` Dexuan Cui
2019-09-27 9:05 ` Vitaly Kuznetsov
2019-09-30 18:49 ` Dexuan Cui
2019-09-05 22:47 ` [PATCH v5 2/3] x86/hyper-v: Implement hv_is_hibernation_supported() Dexuan Cui
2019-09-05 22:47 ` [PATCH v5 3/3] clocksource/drivers: Suspend/resume Hyper-V clocksource for hibernation Dexuan Cui
2019-09-25 23:21 ` Daniel Lezcano
2019-09-25 23:35 ` Dexuan Cui
2019-09-26 13:16 ` Daniel Lezcano
2019-09-27 5:57 ` Dexuan Cui
2019-09-25 22:49 ` [PATCH v5 0/3] Enhance Hyper-V " Dexuan Cui
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87ef0372wv.fsf@vitty.brq.redhat.com \
--to=vkuznets@redhat.com \
--cc=Alexander.Levin@microsoft.com \
--cc=arnd@arndb.de \
--cc=bp@alien8.de \
--cc=daniel.lezcano@linaro.org \
--cc=decui@microsoft.com \
--cc=haiyangz@microsoft.com \
--cc=hpa@zytor.com \
--cc=kys@microsoft.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mikelley@microsoft.com \
--cc=mingo@redhat.com \
--cc=sashal@kernel.org \
--cc=sthemmin@microsoft.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).