From: Vitaly Kuznetsov vkuznets@redhat.com

mainline inclusion from mainline-v5.13-rc2 commit 8b79feffeca28c5459458fe78676b081e87c93a4 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I990AA CVE: CVE-2021-47112

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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Various PV features (Async PF, PV EOI, steal time) work through memory shared with hypervisor and when we restore from hibernation we must properly teardown all these features to make sure hypervisor doesn't write to stale locations after we jump to the previously hibernated kernel (which can try to place anything there). For secondary CPUs the job is already done by kvm_cpu_down_prepare(), register syscore ops to do the same for boot CPU.

Signed-off-by: Vitaly Kuznetsov vkuznets@redhat.com Message-Id: 20210414123544.1060604-3-vkuznets@redhat.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- arch/x86/kernel/kvm.c | 57 +++++++++++++++++++++++++++++++------------ 1 file changed, 41 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index d1ccd5bbf623..1f430ebce6db 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -37,6 +37,7 @@ #include <linux/debugfs.h> #include <linux/nmi.h> #include <linux/swait.h> +#include <linux/syscore_ops.h> #include <asm/timer.h> #include <asm/cpu.h> #include <asm/traps.h> @@ -444,6 +445,25 @@ static void __init sev_map_percpu_data(void) } }

+static void kvm_guest_cpu_offline(void) +{ + kvm_disable_steal_time(); + if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) + wrmsrl(MSR_KVM_PV_EOI_EN, 0); + kvm_pv_disable_apf(); + apf_task_wake_all(); +} + +static int kvm_cpu_online(unsigned int cpu) +{ + unsigned long flags; + + local_irq_save(flags); + kvm_guest_cpu_init(); + local_irq_restore(flags); + return 0; +} + #ifdef CONFIG_SMP #define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG)

@@ -560,31 +580,34 @@ static void __init kvm_smp_prepare_boot_cpu(void) kvm_spinlock_init(); }

-static void kvm_guest_cpu_offline(void) +static int kvm_cpu_down_prepare(unsigned int cpu) { - kvm_disable_steal_time(); - if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) - wrmsrl(MSR_KVM_PV_EOI_EN, 0); - kvm_pv_disable_apf(); - apf_task_wake_all(); -} + unsigned long flags;

-static int kvm_cpu_online(unsigned int cpu) -{ - local_irq_disable(); - kvm_guest_cpu_init(); - local_irq_enable(); + local_irq_save(flags); + kvm_guest_cpu_offline(); + local_irq_restore(flags); return 0; }

-static int kvm_cpu_down_prepare(unsigned int cpu) +#endif + +static int kvm_suspend(void) { - local_irq_disable(); kvm_guest_cpu_offline(); - local_irq_enable(); + return 0; + } + +static void kvm_resume(void) +{ + kvm_cpu_online(raw_smp_processor_id()); } -#endif + +static struct syscore_ops kvm_syscore_ops = { + .suspend = kvm_suspend, + .resume = kvm_resume, +};

static void __init kvm_apf_trap_init(void) { @@ -659,6 +682,8 @@ static void __init kvm_guest_init(void) kvm_guest_cpu_init(); #endif

+ register_syscore_ops(&kvm_syscore_ops); + /* * Hard lockup detection is enabled by default. Disable it, as guests * can get false positives too easily, for example if the host is