From: Dmitry Safonov <dima@arista.com>
To: linux-kernel@vger.kernel.org
Cc: "Dmitry Safonov" <0x7f454c46@gmail.com>,
"Dmitry Safonov" <dima@arista.com>,
"Prasanna Panchamukhi" <panchamukhi@arista.com>,
"Andy Lutomirski" <luto@kernel.org>,
"Borislav Petkov" <bp@alien8.de>,
"Cathy Avery" <cavery@redhat.com>,
"Haiyang Zhang" <haiyangz@microsoft.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"Ingo Molnar" <mingo@redhat.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
"Michael Kelley (EOSG)" <Michael.H.Kelley@microsoft.com>,
"Mohammed Gamal" <mmorsy@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Roman Kagan" <rkagan@virtuozzo.com>,
"Sasha Levin" <sashal@kernel.org>,
"Stephen Hemminger" <sthemmin@microsoft.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Vitaly Kuznetsov" <vkuznets@redhat.com>,
devel@linuxdriverproject.org, kvm@vger.kernel.org,
linux-hyperv@vger.kernel.org, x86@kernel.org
Subject: [PATCHv2] x86/hyperv: Hold cpus_read_lock() on assigning reenlightenment vector
Date: Mon, 17 Jun 2019 17:39:55 +0100 [thread overview]
Message-ID: <20190617163955.25659-1-dima@arista.com> (raw)
KVM support may be compiled as dynamic module, which triggers the
following splat on modprobe (under CONFIG_DEBUG_PREEMPT):
KVM: vmx: using Hyper-V Enlightened VMCS
BUG: using smp_processor_id() in preemptible [00000000] code: modprobe/466
caller is debug_smp_processor_id+0x17/0x19
CPU: 0 PID: 466 Comm: modprobe Kdump: loaded Not tainted 4.19.43 #1
Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS 090007 06/02/2017
Call Trace:
dump_stack+0x61/0x7e
check_preemption_disabled+0xd4/0xe6
debug_smp_processor_id+0x17/0x19
set_hv_tscchange_cb+0x1b/0x89
kvm_arch_init+0x14a/0x163 [kvm]
kvm_init+0x30/0x259 [kvm]
vmx_init+0xed/0x3db [kvm_intel]
do_one_initcall+0x89/0x1bc
do_init_module+0x5f/0x207
load_module+0x1b34/0x209b
__ia32_sys_init_module+0x17/0x19
do_fast_syscall_32+0x121/0x1fa
entry_SYSENTER_compat+0x7f/0x91
Hold cpus_read_lock() so that MSR will be written for an online CPU,
even if set_hv_tscchange_cb() gets being preempted.
While at it, cleanup smp_processor_id()'s in hv_cpu_init() and add a
lockdep assert into hv_cpu_die().
Fixes: 93286261de1b4 ("x86/hyperv: Reenlightenment notifications
support")
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Cathy Avery <cavery@redhat.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: "Michael Kelley (EOSG)" <Michael.H.Kelley@microsoft.com>
Cc: Mohammed Gamal <mmorsy@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Roman Kagan <rkagan@virtuozzo.com>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: devel@linuxdriverproject.org
Cc: kvm@vger.kernel.org
Cc: linux-hyperv@vger.kernel.org
Cc: x86@kernel.org
Reported-by: Prasanna Panchamukhi <panchamukhi@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
v1 link: lkml.kernel.org/r/20190611212003.26382-1-dima@arista.com
NOTE that I hadn't a chance to test v2 on hyperv machine so far,
ONLY BUILD TESTED. (In hope that the patch still makes sense and Kbuild
bot will report any issue).
arch/x86/hyperv/hv_init.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 1608050e9df9..ec7fd7d6c125 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -20,6 +20,7 @@
#include <linux/clockchips.h>
#include <linux/hyperv.h>
#include <linux/slab.h>
+#include <linux/cpu.h>
#include <linux/cpuhotplug.h>
#ifdef CONFIG_HYPERV_TSCPAGE
@@ -91,7 +92,7 @@ EXPORT_SYMBOL_GPL(hv_max_vp_index);
static int hv_cpu_init(unsigned int cpu)
{
u64 msr_vp_index;
- struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
+ struct hv_vp_assist_page **hvp = &hv_vp_assist_page[cpu];
void **input_arg;
struct page *pg;
@@ -103,7 +104,7 @@ static int hv_cpu_init(unsigned int cpu)
hv_get_vp_index(msr_vp_index);
- hv_vp_index[smp_processor_id()] = msr_vp_index;
+ hv_vp_index[cpu] = msr_vp_index;
if (msr_vp_index > hv_max_vp_index)
hv_max_vp_index = msr_vp_index;
@@ -182,7 +183,6 @@ void set_hv_tscchange_cb(void (*cb)(void))
struct hv_reenlightenment_control re_ctrl = {
.vector = HYPERV_REENLIGHTENMENT_VECTOR,
.enabled = 1,
- .target_vp = hv_vp_index[smp_processor_id()]
};
struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
@@ -196,7 +196,16 @@ void set_hv_tscchange_cb(void (*cb)(void))
/* Make sure callback is registered before we write to MSRs */
wmb();
+ /*
+ * As reenlightenment vector is global, there is no difference which
+ * CPU will register MSR, though it should be an online CPU.
+ * hv_cpu_die() callback guarantees that on CPU teardown
+ * another CPU will re-register MSR back.
+ */
+ cpus_read_lock();
+ re_ctrl.target_vp = hv_vp_index[raw_smp_processor_id()];
wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
+ cpus_read_unlock();
wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
}
EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
@@ -239,6 +248,7 @@ static int hv_cpu_die(unsigned int cpu)
rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
if (re_ctrl.target_vp == hv_vp_index[cpu]) {
+ lockdep_assert_cpus_held();
/* Reassign to some other online CPU */
new_cpu = cpumask_any_but(cpu_online_mask, cpu);
--
2.22.0
next reply other threads:[~2019-06-17 16:40 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-17 16:39 Dmitry Safonov [this message]
2019-06-27 22:39 ` [PATCHv2] x86/hyperv: Hold cpus_read_lock() on assigning reenlightenment vector Thomas Gleixner
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=20190617163955.25659-1-dima@arista.com \
--to=dima@arista.com \
--cc=0x7f454c46@gmail.com \
--cc=Michael.H.Kelley@microsoft.com \
--cc=bp@alien8.de \
--cc=cavery@redhat.com \
--cc=devel@linuxdriverproject.org \
--cc=haiyangz@microsoft.com \
--cc=hpa@zytor.com \
--cc=kvm@vger.kernel.org \
--cc=kys@microsoft.com \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mingo@redhat.com \
--cc=mmorsy@redhat.com \
--cc=panchamukhi@arista.com \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.org \
--cc=rkagan@virtuozzo.com \
--cc=rkrcmar@redhat.com \
--cc=sashal@kernel.org \
--cc=sthemmin@microsoft.com \
--cc=tglx@linutronix.de \
--cc=vkuznets@redhat.com \
--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).