From: Jason Andryuk <jandryuk@gmail.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: sstabellini@kernel.org, Wei Liu <wei.liu2@citrix.com>,
xen-devel@lists.xen.org, julien.grall@arm.com,
Jan Beulich <JBeulich@suse.com>,
roger.pau@citrix.com
Subject: Re: [PATCH 3/3] xen/vcpu: Rework sanity checks in vcpu_create()
Date: Thu, 6 Sep 2018 16:07:48 -0400 [thread overview]
Message-ID: <CAKf6xpvAYJryWPCjtNPhNbU9v3p1+ihMH=FqoPzb1Nc65KHSCQ@mail.gmail.com> (raw)
In-Reply-To: <1536261934-1236-4-git-send-email-andrew.cooper3@citrix.com>
On Thu, Sep 6, 2018 at 3:28 PM Andrew Cooper <andrew.cooper3@citrix.com> wrote:
>
> Poisoning idle_vcpu[0] with the sanity debug value isn't actually a clever
> idea, because it passes a NULL pointer check but isn't a usable vcpu. It is
> also the reason for the (!is_idle_domain(d) || vcpu_id) part of the existing
> sanity BUG_ON().
>
> Now that d->max_vcpus is appropriately set up before vcpu_create() is called,
> we can properly range check the requested vcpu_id. Drop the BUG_ON() and
> replace it with code which is runtime safe but non-fatal.
>
> While v0 must be the first allocated vcpu for for_each_vcpu() to work, it
> isn't a requirement for the threading the vcpu into the linked list, so update
> the threading code to be more generic, and add a comment explaining why we
> need to search for prev_id.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> ---
> CC: Jan Beulich <JBeulich@suse.com>
> CC: Wei Liu <wei.liu2@citrix.com>
> CC: Roger Pau Monné <roger.pau@citrix.com>
> CC: Stefano Stabellini <sstabellini@kernel.org>
> CC: Julien Grall <julien.grall@arm.com>
> ---
> xen/arch/arm/setup.c | 1 -
> xen/arch/x86/setup.c | 1 -
> xen/common/domain.c | 32 ++++++++++++++++++++++++++++----
> 3 files changed, 28 insertions(+), 6 deletions(-)
>
> diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
> index 01aaaab..d06ac40 100644
> --- a/xen/arch/arm/setup.c
> +++ b/xen/arch/arm/setup.c
> @@ -704,7 +704,6 @@ void __init start_xen(unsigned long boot_phys_offset,
> set_processor_id(0); /* needed early, for smp_processor_id() */
>
> set_current((struct vcpu *)0xfffff000); /* debug sanity */
> - idle_vcpu[0] = current;
>
> setup_virtual_regions(NULL, NULL);
> /* Initialize traps early allow us to get backtrace when an error occurred */
> diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
> index a2f22a1..5e1e8ae 100644
> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -691,7 +691,6 @@ void __init noreturn __start_xen(unsigned long mbi_p)
>
> set_processor_id(0);
> set_current(INVALID_VCPU); /* debug sanity. */
> - idle_vcpu[0] = current;
xen/arch/x86/tboot.c:tboot_shutdown() has:
if ( idle_vcpu[0] != INVALID_VCPU )
write_ptbase(idle_vcpu[0]);
With your change, this should be update to check for non-NULL.
Regards,
Jason
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next prev parent reply other threads:[~2018-09-06 20:07 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-06 19:25 [PATCH 0/3] xen: Improvements to the vcpu create/destroy paths Andrew Cooper
2018-09-06 19:25 ` [PATCH 1/3] xen/vcpu: Rename the common interfaces for consistency Andrew Cooper
2018-09-07 9:52 ` Jan Beulich
2018-09-13 10:29 ` Roger Pau Monné
2018-09-17 1:08 ` Julien Grall
2018-09-06 19:25 ` [PATCH 2/3] xen/vcpu: Introduce vcpu_destroy() Andrew Cooper
2018-09-07 9:53 ` Jan Beulich
2018-09-13 10:32 ` Roger Pau Monné
2018-09-06 19:25 ` [PATCH 3/3] xen/vcpu: Rework sanity checks in vcpu_create() Andrew Cooper
2018-09-06 20:07 ` Jason Andryuk [this message]
2018-09-06 23:01 ` Andrew Cooper
2018-09-07 10:15 ` Jan Beulich
2018-09-07 19:17 ` Andrew Cooper
2018-09-11 16:46 ` [PATCH v2] " Andrew Cooper
2018-09-12 11:38 ` Jason Andryuk
2018-09-12 15:00 ` Jan Beulich
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