From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Marc Zyngier <maz@kernel.org>,
Huacai Chen <chenhuacai@kernel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
Anup Patel <anup@brainfault.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Matthew Rosato <mjrosato@linux.ibm.com>,
Eric Farman <farman@linux.ibm.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
David Woodhouse <dwmw2@infradead.org>,
Paul Durrant <paul@xen.org>
Cc: kvm@vger.kernel.org, "David Hildenbrand" <david@redhat.com>,
"Atish Patra" <atishp@atishpatra.org>,
linux-kernel@vger.kernel.org, "Kai Huang" <kai.huang@intel.com>,
linux-riscv@lists.infradead.org, kvmarm@lists.cs.columbia.edu,
linux-s390@vger.kernel.org, "Chao Gao" <chao.gao@intel.com>,
"Suzuki K Poulose" <suzuki.poulose@arm.com>,
"Yuan Yao" <yuan.yao@intel.com>,
kvmarm@lists.linux.dev, "Thomas Gleixner" <tglx@linutronix.de>,
"Alexandru Elisei" <alexandru.elisei@arm.com>,
linux-arm-kernel@lists.infradead.org,
"Isaku Yamahata" <isaku.yamahata@intel.com>,
"Philippe Mathieu-Daudé" <philmd@linaro.org>,
"Fabiano Rosas" <farosas@linux.ibm.com>,
"Cornelia Huck" <cohuck@redhat.com>,
linux-mips@vger.kernel.org,
"Oliver Upton" <oliver.upton@linux.dev>,
"James Morse" <james.morse@arm.com>,
kvm-riscv@lists.infradead.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v2 42/50] KVM: Disable CPU hotplug during hardware enabling/disabling
Date: Wed, 30 Nov 2022 23:09:26 +0000 [thread overview]
Message-ID: <20221130230934.1014142-43-seanjc@google.com> (raw)
In-Reply-To: <20221130230934.1014142-1-seanjc@google.com>
From: Chao Gao <chao.gao@intel.com>
Disable CPU hotplug when enabling/disabling hardware to prevent the
corner case where if the following sequence occurs:
1. A hotplugged CPU marks itself online in cpu_online_mask
2. The hotplugged CPU enables interrupt before invoking KVM's ONLINE
callback
3 hardware_{en,dis}able_all() is invoked on another CPU
the hotplugged CPU will be included in on_each_cpu() and thus get sent
through hardware_{en,dis}able_nolock() before kvm_online_cpu() is called.
start_secondary { ...
set_cpu_online(smp_processor_id(), true); <- 1
...
local_irq_enable(); <- 2
...
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); <- 3
}
KVM currently fudges around this race by keeping track of which CPUs have
done hardware enabling (see commit 1b6c016818a5 "KVM: Keep track of which
cpus have virtualization enabled"), but that's an inefficient, convoluted,
and hacky solution.
Signed-off-by: Chao Gao <chao.gao@intel.com>
[sean: split to separate patch, write changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/x86.c | 11 ++++++++++-
virt/kvm/kvm_main.c | 12 ++++++++++++
2 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index dad30097f0c3..d2ad383da998 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9281,7 +9281,16 @@ static inline void kvm_ops_update(struct kvm_x86_init_ops *ops)
static int kvm_x86_check_processor_compatibility(void)
{
- struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
+ int cpu = smp_processor_id();
+ struct cpuinfo_x86 *c = &cpu_data(cpu);
+
+ /*
+ * Compatibility checks are done when loading KVM and when enabling
+ * hardware, e.g. during CPU hotplug, to ensure all online CPUs are
+ * compatible, i.e. KVM should never perform a compatibility check on
+ * an offline CPU.
+ */
+ WARN_ON(!cpu_online(cpu));
if (__cr4_reserved_bits(cpu_has, c) !=
__cr4_reserved_bits(cpu_has, &boot_cpu_data))
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f26ea779710a..d985b24c423b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5098,15 +5098,26 @@ static void hardware_disable_all_nolock(void)
static void hardware_disable_all(void)
{
+ cpus_read_lock();
raw_spin_lock(&kvm_count_lock);
hardware_disable_all_nolock();
raw_spin_unlock(&kvm_count_lock);
+ cpus_read_unlock();
}
static int hardware_enable_all(void)
{
int r = 0;
+ /*
+ * When onlining a CPU, cpu_online_mask is set before kvm_online_cpu()
+ * is called, and so on_each_cpu() between them includes the CPU that
+ * is being onlined. As a result, hardware_enable_nolock() may get
+ * invoked before kvm_online_cpu(), which also enables hardware if the
+ * usage count is non-zero. Disable CPU hotplug to avoid attempting to
+ * enable hardware multiple times.
+ */
+ cpus_read_lock();
raw_spin_lock(&kvm_count_lock);
kvm_usage_count++;
@@ -5121,6 +5132,7 @@ static int hardware_enable_all(void)
}
raw_spin_unlock(&kvm_count_lock);
+ cpus_read_unlock();
return r;
}
--
2.38.1.584.g0f3c55d4c2-goog
next prev parent reply other threads:[~2022-11-30 23:56 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-30 23:08 [PATCH v2 00/50] KVM: Rework kvm_init() and hardware enabling Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 01/50] KVM: Register /dev/kvm as the _very_ last thing during initialization Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 02/50] KVM: Initialize IRQ FD after arch hardware setup Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 03/50] KVM: Allocate cpus_hardware_enabled " Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 04/50] KVM: Teardown VFIO ops earlier in kvm_exit() Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 05/50] KVM: s390: Unwind kvm_arch_init() piece-by-piece() if a step fails Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 06/50] KVM: s390: Move hardware setup/unsetup to init/exit Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 07/50] KVM: x86: Do timer initialization after XCR0 configuration Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 08/50] KVM: x86: Move hardware setup/unsetup to init/exit Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 09/50] KVM: Drop arch hardware (un)setup hooks Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 10/50] KVM: VMX: Reset eVMCS controls in VP assist page during hardware disabling Sean Christopherson
2022-12-01 15:42 ` Vitaly Kuznetsov
2022-11-30 23:08 ` [PATCH v2 11/50] KVM: VMX: Don't bother disabling eVMCS static key on module exit Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 12/50] KVM: VMX: Move Hyper-V eVMCS initialization to helper Sean Christopherson
2022-12-01 15:22 ` Vitaly Kuznetsov
2022-11-30 23:08 ` [PATCH v2 13/50] KVM: x86: Move guts of kvm_arch_init() to standalone helper Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 14/50] KVM: VMX: Do _all_ initialization before exposing /dev/kvm to userspace Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 15/50] KVM: x86: Serialize vendor module initialization (hardware setup) Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 16/50] KVM: arm64: Simplify the CPUHP logic Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 17/50] KVM: arm64: Free hypervisor allocations if vector slot init fails Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 18/50] KVM: arm64: Unregister perf callbacks if hypervisor finalization fails Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 19/50] KVM: arm64: Do arm/arch initialization without bouncing through kvm_init() Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 20/50] KVM: arm64: Mark kvm_arm_init() and its unique descendants as __init Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 21/50] KVM: MIPS: Hardcode callbacks to hardware virtualization extensions Sean Christopherson
2022-12-01 22:00 ` Philippe Mathieu-Daudé
2022-12-01 22:49 ` Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 22/50] KVM: MIPS: Setup VZ emulation? directly from kvm_mips_init() Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 23/50] KVM: MIPS: Register die notifier prior to kvm_init() Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 24/50] KVM: RISC-V: Do arch init directly in riscv_kvm_init() Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 25/50] KVM: RISC-V: Tag init functions and data with __init, __ro_after_init Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 26/50] KVM: PPC: Move processor compatibility check to module init Sean Christopherson
2022-12-01 5:21 ` Michael Ellerman
2022-12-01 16:38 ` Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 27/50] KVM: s390: Do s390 specific init without bouncing through kvm_init() Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 28/50] KVM: s390: Mark __kvm_s390_init() and its descendants as __init Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 29/50] KVM: Drop kvm_arch_{init,exit}() hooks Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 30/50] KVM: VMX: Make VMCS configuration/capabilities structs read-only after init Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 31/50] KVM: x86: Do CPU compatibility checks in x86 code Sean Christopherson
2022-12-02 12:16 ` Huang, Kai
2022-12-05 20:52 ` Isaku Yamahata
2022-12-05 21:12 ` Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 32/50] KVM: Drop kvm_arch_check_processor_compat() hook Sean Christopherson
2022-12-02 12:18 ` Huang, Kai
2022-11-30 23:09 ` [PATCH v2 33/50] KVM: x86: Use KBUILD_MODNAME to specify vendor module name Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 34/50] KVM: x86: Unify pr_fmt to use module name for all KVM modules Sean Christopherson
2022-12-01 10:43 ` Paul Durrant
2022-11-30 23:09 ` [PATCH v2 35/50] KVM: VMX: Use current CPU's info to perform "disabled by BIOS?" checks Sean Christopherson
2022-12-02 12:18 ` Huang, Kai
2022-11-30 23:09 ` [PATCH v2 36/50] KVM: x86: Do VMX/SVM support checks directly in vendor code Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 37/50] KVM: VMX: Shuffle support checks and hardware enabling code around Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 38/50] KVM: SVM: Check for SVM support in CPU compatibility checks Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 39/50] KVM: x86: Move CPU compat checks hook to kvm_x86_ops (from kvm_x86_init_ops) Sean Christopherson
2022-12-02 13:01 ` Huang, Kai
2022-12-05 21:04 ` Isaku Yamahata
2022-11-30 23:09 ` [PATCH v2 40/50] KVM: x86: Do compatibility checks when onlining CPU Sean Christopherson
2022-12-02 13:03 ` Huang, Kai
2022-12-02 13:36 ` Huang, Kai
2022-12-02 16:04 ` Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 41/50] KVM: Rename and move CPUHP_AP_KVM_STARTING to ONLINE section Sean Christopherson
2022-12-02 13:06 ` Huang, Kai
2022-12-02 16:08 ` Sean Christopherson
2022-11-30 23:09 ` Sean Christopherson [this message]
2022-12-02 12:59 ` [PATCH v2 42/50] KVM: Disable CPU hotplug during hardware enabling/disabling Huang, Kai
2022-12-02 16:31 ` Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 43/50] KVM: Ensure CPU is stable during low level hardware enable/disable Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 44/50] KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 45/50] KVM: Remove on_each_cpu(hardware_disable_nolock) in kvm_exit() Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 46/50] KVM: Use a per-CPU variable to track which CPUs have enabled virtualization Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 47/50] KVM: Make hardware_enable_failed a local variable in the "enable all" path Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 48/50] KVM: Register syscore (suspend/resume) ops early in kvm_init() Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 49/50] KVM: Opt out of generic hardware enabling on s390 and PPC Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 50/50] KVM: Clean up error labels in kvm_init() Sean Christopherson
2022-12-02 8:02 ` [PATCH v2 00/50] KVM: Rework kvm_init() and hardware enabling Chao Gao
2022-12-27 13:02 ` Paolo Bonzini
2022-12-28 11:22 ` Marc Zyngier
2022-12-28 11:58 ` Paolo Bonzini
2022-12-29 20:52 ` Paolo Bonzini
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