From: Wanpeng Li <kernellwp@gmail.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Brijesh Singh <brijesh.singh@amd.com>
Subject: [PATCH v2] KVM: kvmclock: Fix vCPUs > 64 can't be online/hotpluged
Date: Mon, 18 Jan 2021 17:07:53 +0800 [thread overview]
Message-ID: <1610960877-3110-1-git-send-email-wanpengli@tencent.com> (raw)
From: Wanpeng Li <wanpengli@tencent.com>
The per-cpu vsyscall pvclock data pointer assigns either an element of the
static array hv_clock_boot (#vCPU <= 64) or dynamically allocated memory
hvclock_mem (vCPU > 64), the dynamically memory will not be allocated if
kvmclock vsyscall is disabled, this can result in cpu hotpluged fails in
kvmclock_setup_percpu() which returns -ENOMEM. This patch fixes it by not
assigning vsyscall pvclock data pointer if kvmclock vdso_clock_mode is not
VDSO_CLOCKMODE_PVCLOCK.
Fixes: 6a1cac56f4 ("x86/kvm: Use __bss_decrypted attribute in shared variables")
Reported-by: Zelin Deng <zelin.deng@linux.alibaba.com>
Tested-by: Haiwei Li <lihaiwei@tencent.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: stable@vger.kernel.org#v4.19-rc5+
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
v1 -> v2:
* add code comments
arch/x86/kernel/kvmclock.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index aa59374..01d4e55c 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -294,9 +294,11 @@ static int kvmclock_setup_percpu(unsigned int cpu)
/*
* The per cpu area setup replicates CPU0 data to all cpu
* pointers. So carefully check. CPU0 has been set up in init
- * already.
+ * already. Assign vsyscall pvclock data pointer iff kvmclock
+ * vsyscall is enabled.
*/
- if (!cpu || (p && p != per_cpu(hv_clock_per_cpu, 0)))
+ if (!cpu || (p && p != per_cpu(hv_clock_per_cpu, 0)) ||
+ (kvm_clock.vdso_clock_mode != VDSO_CLOCKMODE_PVCLOCK))
return 0;
/* Use the static page for the first CPUs, allocate otherwise */
--
2.7.4
next reply other threads:[~2021-01-18 9:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-18 9:07 Wanpeng Li [this message]
2021-01-26 1:28 ` [PATCH v2] KVM: kvmclock: Fix vCPUs > 64 can't be online/hotpluged Wanpeng Li
2021-01-26 17:26 ` Paolo Bonzini
2021-01-27 0:28 ` Wanpeng Li
2021-01-28 7:41 ` Wanpeng Li
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