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-rw-r--r--common/recipes-kernel/linux/linux-yocto-4.9.21/0029-KVM-async_pf-Fix-DF-due-to-inject-Page-not-Present-a.patch105
1 files changed, 105 insertions, 0 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0029-KVM-async_pf-Fix-DF-due-to-inject-Page-not-Present-a.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0029-KVM-async_pf-Fix-DF-due-to-inject-Page-not-Present-a.patch
new file mode 100644
index 00000000..b50d5453
--- /dev/null
+++ b/common/recipes-kernel/linux/linux-yocto-4.9.21/0029-KVM-async_pf-Fix-DF-due-to-inject-Page-not-Present-a.patch
@@ -0,0 +1,105 @@
+From 8e13680f134458dd1b0529ccb636ae5895fa8a4d Mon Sep 17 00:00:00 2001
+From: Wanpeng Li <wanpeng.li@hotmail.com>
+Date: Thu, 14 Sep 2017 03:54:16 -0700
+Subject: [PATCH 29/33] KVM: async_pf: Fix #DF due to inject "Page not Present"
+ and "Page Ready" exceptions simultaneously
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+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>
+---
+ arch/x86/kvm/x86.c | 34 ++++++++++++++++++++++++++--------
+ 1 file changed, 26 insertions(+), 8 deletions(-)
+
+diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
+index af333e1..9f0f7e2 100644
+--- a/arch/x86/kvm/x86.c
++++ b/arch/x86/kvm/x86.c
+@@ -8370,6 +8370,13 @@ 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)
+ {
+@@ -8396,6 +8403,7 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
+ struct kvm_async_pf *work)
+ {
+ struct x86_exception fault;
++ u32 val;
+
+ trace_kvm_async_pf_ready(work->arch.token, work->gva);
+ if (work->wakeup_all)
+@@ -8403,14 +8411,24 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
+ else
+ kvm_del_async_pf_gfn(vcpu, work->arch.gfn);
+
+- 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;
+--
+2.7.4
+