projects / thirdparty / kernel / stable-queue.git / blame
| Commit | Line | Data |
|---|---|---|
| 68718636 GKH |
1 | From fe2a3027e74e40a3ece3a4c1e4e51403090a907a Mon Sep 17 00:00:00 2001 |
| 2 | From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= <rkrcmar@redhat.com> | |
| 3 | Date: Thu, 1 Feb 2018 22:16:21 +0100 | |
| 4 | Subject: KVM: x86: fix backward migration with async_PF | |
| 5 | MIME-Version: 1.0 | |
| 6 | Content-Type: text/plain; charset=UTF-8 | |
| 7 | Content-Transfer-Encoding: 8bit | |
| 8 | ||
| 9 | From: Radim Krčmář <rkrcmar@redhat.com> | |
| 10 | ||
| 11 | commit fe2a3027e74e40a3ece3a4c1e4e51403090a907a upstream. | |
| 12 | ||
| 13 | Guests on new hypersiors might set KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT | |
| 14 | bit when enabling async_PF, but this bit is reserved on old hypervisors, | |
| 15 | which results in a failure upon migration. | |
| 16 | ||
| 17 | To avoid breaking different cases, we are checking for CPUID feature bit | |
| 18 | before enabling the feature and nothing else. | |
| 19 | ||
| 20 | Fixes: 52a5c155cf79 ("KVM: async_pf: Let guest support delivery of async_pf from guest mode") | |
| 21 | Cc: <stable@vger.kernel.org> | |
| 22 | Reviewed-by: Wanpeng Li <wanpengli@tencent.com> | |
| 23 | Reviewed-by: David Hildenbrand <david@redhat.com> | |
| 24 | Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> | |
| 25 | Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> | |
| 26 | [jwang: port to 4.14] | |
| 27 | Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com> | |
| 28 | Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
| 29 | --- | |
| 30 | Documentation/virtual/kvm/cpuid.txt | 4 ++++ | |
| 31 | Documentation/virtual/kvm/msr.txt | 3 ++- | |
| 32 | arch/x86/include/uapi/asm/kvm_para.h | 1 + | |
| 33 | arch/x86/kernel/kvm.c | 8 ++++---- | |
| 34 | arch/x86/kvm/cpuid.c | 3 ++- | |
| 35 | 5 files changed, 13 insertions(+), 6 deletions(-) | |
| 36 | ||
| 37 | --- a/Documentation/virtual/kvm/cpuid.txt | |
| 38 | +++ b/Documentation/virtual/kvm/cpuid.txt | |
| 39 | @@ -54,6 +54,10 @@ KVM_FEATURE_PV_UNHALT || | |
| 40 | || || before enabling paravirtualized | |
| 41 | || || spinlock support. | |
| 42 | ------------------------------------------------------------------------------ | |
| 43 | +KVM_FEATURE_ASYNC_PF_VMEXIT || 10 || paravirtualized async PF VM exit | |
| 44 | + || || can be enabled by setting bit 2 | |
| 45 | + || || when writing to msr 0x4b564d02 | |
| 46 | +------------------------------------------------------------------------------ | |
| 47 | KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side | |
| 48 | || || per-cpu warps are expected in | |
| 49 | || || kvmclock. | |
| 50 | --- a/Documentation/virtual/kvm/msr.txt | |
| 51 | +++ b/Documentation/virtual/kvm/msr.txt | |
| 52 | @@ -170,7 +170,8 @@ MSR_KVM_ASYNC_PF_EN: 0x4b564d02 | |
| 53 | when asynchronous page faults are enabled on the vcpu 0 when | |
| 54 | disabled. Bit 1 is 1 if asynchronous page faults can be injected | |
| 55 | when vcpu is in cpl == 0. Bit 2 is 1 if asynchronous page faults | |
| 56 | - are delivered to L1 as #PF vmexits. | |
| 57 | + are delivered to L1 as #PF vmexits. Bit 2 can be set only if | |
| 58 | + KVM_FEATURE_ASYNC_PF_VMEXIT is present in CPUID. | |
| 59 | ||
| 60 | First 4 byte of 64 byte memory location will be written to by | |
| 61 | the hypervisor at the time of asynchronous page fault (APF) | |
| 62 | --- a/arch/x86/include/uapi/asm/kvm_para.h | |
| 63 | +++ b/arch/x86/include/uapi/asm/kvm_para.h | |
| 64 | @@ -25,6 +25,7 @@ | |
| 65 | #define KVM_FEATURE_STEAL_TIME 5 | |
| 66 | #define KVM_FEATURE_PV_EOI 6 | |
| 67 | #define KVM_FEATURE_PV_UNHALT 7 | |
| 68 | +#define KVM_FEATURE_ASYNC_PF_VMEXIT 10 | |
| 69 | ||
| 70 | /* The last 8 bits are used to indicate how to interpret the flags field | |
| 71 | * in pvclock structure. If no bits are set, all flags are ignored. | |
| 72 | --- a/arch/x86/kernel/kvm.c | |
| 73 | +++ b/arch/x86/kernel/kvm.c | |
| 74 | @@ -341,10 +341,10 @@ static void kvm_guest_cpu_init(void) | |
| 75 | #endif | |
| 76 | pa |= KVM_ASYNC_PF_ENABLED; | |
| 77 | ||
| 78 | - /* Async page fault support for L1 hypervisor is optional */ | |
| 79 | - if (wrmsr_safe(MSR_KVM_ASYNC_PF_EN, | |
| 80 | - (pa | KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT) & 0xffffffff, pa >> 32) < 0) | |
| 81 | - wrmsrl(MSR_KVM_ASYNC_PF_EN, pa); | |
| 82 | + if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT)) | |
| 83 | + pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT; | |
| 84 | + | |
| 85 | + wrmsrl(MSR_KVM_ASYNC_PF_EN, pa); | |
| 86 | __this_cpu_write(apf_reason.enabled, 1); | |
| 87 | printk(KERN_INFO"KVM setup async PF for cpu %d\n", | |
| 88 | smp_processor_id()); | |
| 89 | --- a/arch/x86/kvm/cpuid.c | |
| 90 | +++ b/arch/x86/kvm/cpuid.c | |
| 91 | @@ -597,7 +597,8 @@ static inline int __do_cpuid_ent(struct | |
| 92 | (1 << KVM_FEATURE_ASYNC_PF) | | |
| 93 | (1 << KVM_FEATURE_PV_EOI) | | |
| 94 | (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) | | |
| 95 | - (1 << KVM_FEATURE_PV_UNHALT); | |
| 96 | + (1 << KVM_FEATURE_PV_UNHALT) | | |
| 97 | + (1 << KVM_FEATURE_ASYNC_PF_VMEXIT); | |
| 98 | ||
| 99 | if (sched_info_on()) | |
| 100 | entry->eax |= (1 << KVM_FEATURE_STEAL_TIME); |