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authorWanpeng Li <wanpeng.li@hotmail.com>2017-09-14 03:54:16 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-02-25 11:05:56 +0100
commitafff83e6733b50803c26ac761bbc0926848939e9 (patch)
treeee6fd5546b473549e0a27ad766a220b9653d3067
parent1acf767c213a0be16a9e1bacb140dd5bf0bb644a (diff)
KVM: async_pf: Fix #DF due to inject "Page not Present" and "Page Ready" exceptions simultaneously
commit 9a6e7c39810e4a8bc7fc95056cefb40583fe07ef upstream. qemu-system-x86-8600 [004] d..1 7205.687530: kvm_entry: vcpu 2 qemu-system-x86-8600 [004] .... 7205.687532: kvm_exit: reason EXCEPTION_NMI rip 0xffffffffa921297d info ffffeb2c0e44e018 80000b0e qemu-system-x86-8600 [004] .... 7205.687532: kvm_page_fault: address ffffeb2c0e44e018 error_code 0 qemu-system-x86-8600 [004] .... 7205.687620: kvm_try_async_get_page: gva = 0xffffeb2c0e44e018, gfn = 0x427e4e qemu-system-x86-8600 [004] .N.. 7205.687628: kvm_async_pf_not_present: token 0x8b002 gva 0xffffeb2c0e44e018 kworker/4:2-7814 [004] .... 7205.687655: kvm_async_pf_completed: gva 0xffffeb2c0e44e018 address 0x7fcc30c4e000 qemu-system-x86-8600 [004] .... 7205.687703: kvm_async_pf_ready: token 0x8b002 gva 0xffffeb2c0e44e018 qemu-system-x86-8600 [004] d..1 7205.687711: kvm_entry: vcpu 2 After running some memory intensive workload in guest, I catch the kworker which completes the GUP too quickly, and queues an "Page Ready" #PF exception after the "Page not Present" exception before the next vmentry as the above trace which will result in #DF injected to guest. This patch fixes it by clearing the queue for "Page not Present" if "Page Ready" occurs before the next vmentry since the GUP has already got the required page and shadow page table has already been fixed by "Page Ready" handler. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Fixes: 7c90705bf2a3 ("KVM: Inject asynchronous page fault into a PV guest if page is swapped out.") [Changed indentation and added clearing of injected. - Radim] Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> [port from upstream v4.14-rc1, Don't assign to kvm_queued_exception::injected or x86_exception::async_page_fault] Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/kvm/x86.c34
1 files changed, 26 insertions, 8 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8a40165b1b1e..4b19ec1da22d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8427,6 +8427,13 @@ static int apf_put_user(struct kvm_vcpu *vcpu, u32 val)
sizeof(val));
}
+static int apf_get_user(struct kvm_vcpu *vcpu, u32 *val)
+{
+
+ return kvm_read_guest_cached(vcpu->kvm, &vcpu->arch.apf.data, val,
+ sizeof(u32));
+}
+
void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu,
struct kvm_async_pf *work)
{
@@ -8453,6 +8460,7 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
struct kvm_async_pf *work)
{
struct x86_exception fault;
+ u32 val;
if (work->wakeup_all)
work->arch.token = ~0; /* broadcast wakeup */
@@ -8460,14 +8468,24 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
kvm_del_async_pf_gfn(vcpu, work->arch.gfn);
trace_kvm_async_pf_ready(work->arch.token, work->gva);
- if ((vcpu->arch.apf.msr_val & KVM_ASYNC_PF_ENABLED) &&
- !apf_put_user(vcpu, KVM_PV_REASON_PAGE_READY)) {
- fault.vector = PF_VECTOR;
- fault.error_code_valid = true;
- fault.error_code = 0;
- fault.nested_page_fault = false;
- fault.address = work->arch.token;
- kvm_inject_page_fault(vcpu, &fault);
+ if (vcpu->arch.apf.msr_val & KVM_ASYNC_PF_ENABLED &&
+ !apf_get_user(vcpu, &val)) {
+ if (val == KVM_PV_REASON_PAGE_NOT_PRESENT &&
+ vcpu->arch.exception.pending &&
+ vcpu->arch.exception.nr == PF_VECTOR &&
+ !apf_put_user(vcpu, 0)) {
+ vcpu->arch.exception.pending = false;
+ vcpu->arch.exception.nr = 0;
+ vcpu->arch.exception.has_error_code = false;
+ vcpu->arch.exception.error_code = 0;
+ } else if (!apf_put_user(vcpu, KVM_PV_REASON_PAGE_READY)) {
+ fault.vector = PF_VECTOR;
+ fault.error_code_valid = true;
+ fault.error_code = 0;
+ fault.nested_page_fault = false;
+ fault.address = work->arch.token;
+ kvm_inject_page_fault(vcpu, &fault);
+ }
}
vcpu->arch.apf.halted = false;
vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;