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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id k2sm10057634ejp.6.2021.01.26.09.26.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 Jan 2021 09:26:34 -0800 (PST) To: Wanpeng Li , LKML , kvm Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Brijesh Singh References: <1610960877-3110-1-git-send-email-wanpengli@tencent.com> From: Paolo Bonzini Subject: Re: [PATCH v2] KVM: kvmclock: Fix vCPUs > 64 can't be online/hotpluged Message-ID: <146d2a3f-88db-ff80-29d6-de2b22efdf61@redhat.com> Date: Tue, 26 Jan 2021 18:26:33 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26/01/21 02:28, Wanpeng Li wrote: > pingļ¼Œ > On Mon, 18 Jan 2021 at 17:08, Wanpeng Li wrote: >> >> From: Wanpeng Li >> >> 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. I am sorry, I still cannot figure out this patch. Is hotplug still broken if kvm vsyscall is enabled? Paolo >> Fixes: 6a1cac56f4 ("x86/kvm: Use __bss_decrypted attribute in shared variables") >> Reported-by: Zelin Deng >> Tested-by: Haiwei Li >> Cc: Brijesh Singh >> Cc: stable@vger.kernel.org#v4.19-rc5+ >> Signed-off-by: Wanpeng Li >> --- >> 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 >> >