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From: Wanpeng Li <kernellwp@gmail.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <sean.j.christopherson@intel.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] KVM: kvmclock: Fix vCPUs > 64 can't be online/hotpluged
Date: Thu, 14 Jan 2021 19:27:03 +0800	[thread overview]
Message-ID: <1610623624-18697-1-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 

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>
 arch/x86/kernel/kvmclock.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index aa59374..0624290 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -296,7 +296,8 @@ static int kvmclock_setup_percpu(unsigned int cpu)
 	 * pointers. So carefully check. CPU0 has been set up in init
 	 * already.
-	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 */

             reply	other threads:[~2021-01-14 11:28 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-14 11:27 Wanpeng Li [this message]
2021-01-14 13:45 ` Vitaly Kuznetsov
2021-01-15  1:15   ` Wanpeng Li
2021-01-18 18:26     ` Paolo Bonzini
2021-01-19  0:28       ` Wanpeng Li

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