* [PATCH 0/2] KVM: Only use posted interrupts for Fixes/LowPrio MSIs @ 2019-09-03 14:29 Alexander Graf 2019-09-03 14:29 ` [PATCH 1/2] KVM: VMX: Disable posted interrupts for odd IRQs Alexander Graf 2019-09-03 14:29 ` [PATCH 2/2] KVM: SVM: " Alexander Graf 0 siblings, 2 replies; 6+ messages in thread From: Alexander Graf @ 2019-09-03 14:29 UTC (permalink / raw) To: kvm Cc: linux-kernel, x86, H. Peter Anvin, Borislav Petkov, Ingo Molnar, Thomas Gleixner, Joerg Roedel, Jim Mattson, Wanpeng Li, Vitaly Kuznetsov, Sean Christopherson, Radim Krčmář, Paolo Bonzini The MSI-X descriptor has a "delivery mode" field which can be set to various different targets, such as "Fixed" (default), SMI, NMI or INIT. Usually when we pass devices into guests, we only ever see this MSI-X descriptor configured as Fixed, so nobody realized that the other modes were broken when using posted interrupts. With posted interrupts, we end up configuring these special modes just the same as a Fixed interrupt. That means instead of generating an SMI, we inject a normal GSI into the guest. Of course, that if completely broken. These two patches attempt to fix the situation for x86 systems. If anyone has a great idea how to generalize the filtering though, I'm all ears. Alex Alexander Graf (2): KVM: VMX: Disable posted interrupts for odd IRQs KVM: SVM: Disable posted interrupts for odd IRQs arch/x86/kvm/svm.c | 16 ++++++++++++++++ arch/x86/kvm/vmx/vmx.c | 22 ++++++++++++++++++++++ 2 files changed, 38 insertions(+) -- 2.17.1 Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 1/2] KVM: VMX: Disable posted interrupts for odd IRQs 2019-09-03 14:29 [PATCH 0/2] KVM: Only use posted interrupts for Fixes/LowPrio MSIs Alexander Graf @ 2019-09-03 14:29 ` Alexander Graf 2019-09-03 23:15 ` Liran Alon 2019-09-03 14:29 ` [PATCH 2/2] KVM: SVM: " Alexander Graf 1 sibling, 1 reply; 6+ messages in thread From: Alexander Graf @ 2019-09-03 14:29 UTC (permalink / raw) To: kvm Cc: linux-kernel, x86, H. Peter Anvin, Borislav Petkov, Ingo Molnar, Thomas Gleixner, Joerg Roedel, Jim Mattson, Wanpeng Li, Vitaly Kuznetsov, Sean Christopherson, Radim Krčmář, Paolo Bonzini We can easily route hardware interrupts directly into VM context when they target the "Fixed" or "LowPriority" delivery modes. However, on modes such as "SMI" or "Init", we need to go via KVM code to actually put the vCPU into a different mode of operation, so we can not post the interrupt Add code in the VMX PI logic to explicitly refuse to establish posted mappings for advanced IRQ deliver modes. This fixes a bug I have with code which configures real hardware to inject virtual SMIs into my guest. Signed-off-by: Alexander Graf <graf@amazon.com> --- arch/x86/kvm/vmx/vmx.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 570a233e272b..d16c4ae8f685 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7401,6 +7401,28 @@ static int vmx_update_pi_irte(struct kvm *kvm, unsigned int host_irq, continue; } + switch (irq.delivery_mode) { + case dest_Fixed: + case dest_LowestPrio: + break; + default: + /* + * For non-trivial interrupt events, we need to go + * through the full KVM IRQ code, so refuse to take + * any direct PI assignments here. + */ + + ret = irq_set_vcpu_affinity(host_irq, NULL); + if (ret < 0) { + printk(KERN_INFO + "failed to back to remapped mode, irq: %u\n", + host_irq); + goto out; + } + + continue; + } + vcpu_info.pi_desc_addr = __pa(vcpu_to_pi_desc(vcpu)); vcpu_info.vector = irq.vector; -- 2.17.1 Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] KVM: VMX: Disable posted interrupts for odd IRQs 2019-09-03 14:29 ` [PATCH 1/2] KVM: VMX: Disable posted interrupts for odd IRQs Alexander Graf @ 2019-09-03 23:15 ` Liran Alon 0 siblings, 0 replies; 6+ messages in thread From: Liran Alon @ 2019-09-03 23:15 UTC (permalink / raw) To: Alexander Graf Cc: kvm, linux-kernel, x86, H. Peter Anvin, Borislav Petkov, Ingo Molnar, Thomas Gleixner, Joerg Roedel, Jim Mattson, Wanpeng Li, Vitaly Kuznetsov, Sean Christopherson, Radim Krčmář, Paolo Bonzini > On 3 Sep 2019, at 17:29, Alexander Graf <graf@amazon.com> wrote: > > We can easily route hardware interrupts directly into VM context when > they target the "Fixed" or "LowPriority" delivery modes. > > However, on modes such as "SMI" or "Init", we need to go via KVM code > to actually put the vCPU into a different mode of operation, so we can > not post the interrupt I would also mention in commit message that one can see this is also true in KVM’s vLAPIC code. i.e. __apic_accept_irq() can call kvm_x86_ops->deliver_posted_interrupt() only in case deliver-mode is either “Fixed” or “LowPriority”. > > Add code in the VMX PI logic to explicitly refuse to establish posted > mappings for advanced IRQ deliver modes. > > This fixes a bug I have with code which configures real hardware to > inject virtual SMIs into my guest. > > Signed-off-by: Alexander Graf <graf@amazon.com> With some small improvements I written inline below: Reviewed-by: Liran Alon <liran.alon@oracle.com> > --- > arch/x86/kvm/vmx/vmx.c | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index 570a233e272b..d16c4ae8f685 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -7401,6 +7401,28 @@ static int vmx_update_pi_irte(struct kvm *kvm, unsigned int host_irq, > continue; > } > > + switch (irq.delivery_mode) { > + case dest_Fixed: > + case dest_LowestPrio: > + break; > + default: > + /* > + * For non-trivial interrupt events, we need to go > + * through the full KVM IRQ code, so refuse to take > + * any direct PI assignments here. > + */ > + > + ret = irq_set_vcpu_affinity(host_irq, NULL); > + if (ret < 0) { > + printk(KERN_INFO > + "failed to back to remapped mode, irq: %u\n", > + host_irq); > + goto out; I recommend we will chose to print here a string that is different than the !kvm_intr_is_single_vcpu() case to make it easier to diagnose which case exactly failed. -Liran > + } > + > + continue; > + } > + > vcpu_info.pi_desc_addr = __pa(vcpu_to_pi_desc(vcpu)); > vcpu_info.vector = irq.vector; > > -- > 2.17.1 > > > > > Amazon Development Center Germany GmbH > Krausenstr. 38 > 10117 Berlin > Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich > Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B > Sitz: Berlin > Ust-ID: DE 289 237 879 > > > ^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 2/2] KVM: SVM: Disable posted interrupts for odd IRQs 2019-09-03 14:29 [PATCH 0/2] KVM: Only use posted interrupts for Fixes/LowPrio MSIs Alexander Graf 2019-09-03 14:29 ` [PATCH 1/2] KVM: VMX: Disable posted interrupts for odd IRQs Alexander Graf @ 2019-09-03 14:29 ` Alexander Graf 2019-09-03 23:20 ` Liran Alon 1 sibling, 1 reply; 6+ messages in thread From: Alexander Graf @ 2019-09-03 14:29 UTC (permalink / raw) To: kvm Cc: linux-kernel, x86, H. Peter Anvin, Borislav Petkov, Ingo Molnar, Thomas Gleixner, Joerg Roedel, Jim Mattson, Wanpeng Li, Vitaly Kuznetsov, Sean Christopherson, Radim Krčmář, Paolo Bonzini We can easily route hardware interrupts directly into VM context when they target the "Fixed" or "LowPriority" delivery modes. However, on modes such as "SMI" or "Init", we need to go via KVM code to actually put the vCPU into a different mode of operation, so we can not post the interrupt Add code in the SVM PI logic to explicitly refuse to establish posted mappings for advanced IRQ deliver modes. This fixes a bug I have with code which configures real hardware to inject virtual SMIs into my guest. Signed-off-by: Alexander Graf <graf@amazon.com> --- arch/x86/kvm/svm.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 1f220a85514f..9a6ea78c3239 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -5266,6 +5266,21 @@ get_pi_vcpu_info(struct kvm *kvm, struct kvm_kernel_irq_routing_entry *e, return -1; } + switch (irq.delivery_mode) { + case dest_Fixed: + case dest_LowestPrio: + break; + default: + /* + * For non-trivial interrupt events, we need to go + * through the full KVM IRQ code, so refuse to take + * any direct PI assignments here. + */ + pr_debug("SVM: %s: use legacy intr remap mode for irq %u\n", + __func__, irq.vector); + return -1; + } + pr_debug("SVM: %s: use GA mode for irq %u\n", __func__, irq.vector); *svm = to_svm(vcpu); @@ -5314,6 +5329,7 @@ static int svm_update_pi_irte(struct kvm *kvm, unsigned int host_irq, * 1. When cannot target interrupt to a specific vcpu. * 2. Unsetting posted interrupt. * 3. APIC virtialization is disabled for the vcpu. + * 4. IRQ has extended delivery mode (SMI, INIT, etc) */ if (!get_pi_vcpu_info(kvm, e, &vcpu_info, &svm) && set && kvm_vcpu_apicv_active(&svm->vcpu)) { -- 2.17.1 Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 2/2] KVM: SVM: Disable posted interrupts for odd IRQs 2019-09-03 14:29 ` [PATCH 2/2] KVM: SVM: " Alexander Graf @ 2019-09-03 23:20 ` Liran Alon 2019-09-04 13:06 ` Alexander Graf 0 siblings, 1 reply; 6+ messages in thread From: Liran Alon @ 2019-09-03 23:20 UTC (permalink / raw) To: Alexander Graf Cc: kvm list, linux-kernel, x86, H. Peter Anvin, Borislav Petkov, Ingo Molnar, Thomas Gleixner, Joerg Roedel, Jim Mattson, Wanpeng Li, Vitaly Kuznetsov, Sean Christopherson, Radim Krčmář, Paolo Bonzini > On 3 Sep 2019, at 17:29, Alexander Graf <graf@amazon.com> wrote: > > We can easily route hardware interrupts directly into VM context when > they target the "Fixed" or "LowPriority" delivery modes. > > However, on modes such as "SMI" or "Init", we need to go via KVM code > to actually put the vCPU into a different mode of operation, so we can > not post the interrupt > > Add code in the SVM PI logic to explicitly refuse to establish posted > mappings for advanced IRQ deliver modes. > > This fixes a bug I have with code which configures real hardware to > inject virtual SMIs into my guest. > > Signed-off-by: Alexander Graf <graf@amazon.com> Nit: I prefer to squash both commits into one that change both VMX & SVM. As it’s exactly the same change. > --- > arch/x86/kvm/svm.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 1f220a85514f..9a6ea78c3239 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -5266,6 +5266,21 @@ get_pi_vcpu_info(struct kvm *kvm, struct kvm_kernel_irq_routing_entry *e, > return -1; > } > > + switch (irq.delivery_mode) { > + case dest_Fixed: > + case dest_LowestPrio: > + break; > + default: > + /* > + * For non-trivial interrupt events, we need to go > + * through the full KVM IRQ code, so refuse to take > + * any direct PI assignments here. > + */ > + pr_debug("SVM: %s: use legacy intr remap mode for irq %u\n", > + __func__, irq.vector); > + return -1; > + } > + Prefer changing printed string to something different than the !kvm_intr_is_single_vcpu() case. To assist debugging. Having said that, Reviewed-by: Liran Alon <liran.alon@oracle.com> -Liran > pr_debug("SVM: %s: use GA mode for irq %u\n", __func__, > irq.vector); > *svm = to_svm(vcpu); > @@ -5314,6 +5329,7 @@ static int svm_update_pi_irte(struct kvm *kvm, unsigned int host_irq, > * 1. When cannot target interrupt to a specific vcpu. > * 2. Unsetting posted interrupt. > * 3. APIC virtialization is disabled for the vcpu. > + * 4. IRQ has extended delivery mode (SMI, INIT, etc) > */ > if (!get_pi_vcpu_info(kvm, e, &vcpu_info, &svm) && set && > kvm_vcpu_apicv_active(&svm->vcpu)) { > -- > 2.17.1 > > > > > Amazon Development Center Germany GmbH > Krausenstr. 38 > 10117 Berlin > Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich > Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B > Sitz: Berlin > Ust-ID: DE 289 237 879 > > > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 2/2] KVM: SVM: Disable posted interrupts for odd IRQs 2019-09-03 23:20 ` Liran Alon @ 2019-09-04 13:06 ` Alexander Graf 0 siblings, 0 replies; 6+ messages in thread From: Alexander Graf @ 2019-09-04 13:06 UTC (permalink / raw) To: Liran Alon Cc: kvm list, linux-kernel, x86, H. Peter Anvin, Borislav Petkov, Ingo Molnar, Thomas Gleixner, Joerg Roedel, Jim Mattson, Wanpeng Li, Vitaly Kuznetsov, Sean Christopherson, Radim Krčmář, Paolo Bonzini On 04.09.19 01:20, Liran Alon wrote: > > >> On 3 Sep 2019, at 17:29, Alexander Graf <graf@amazon.com> wrote: >> >> We can easily route hardware interrupts directly into VM context when >> they target the "Fixed" or "LowPriority" delivery modes. >> >> However, on modes such as "SMI" or "Init", we need to go via KVM code >> to actually put the vCPU into a different mode of operation, so we can >> not post the interrupt >> >> Add code in the SVM PI logic to explicitly refuse to establish posted >> mappings for advanced IRQ deliver modes. >> >> This fixes a bug I have with code which configures real hardware to >> inject virtual SMIs into my guest. >> >> Signed-off-by: Alexander Graf <graf@amazon.com> > > Nit: I prefer to squash both commits into one that change both VMX & SVM. > As it’s exactly the same change. It's the same change (hence the same patch set), but they touch different files and so for bisectability it's still convenient to have them as different commits. I'd really prefer to have them stay separate. Thanks a lot for the review! :) Alex Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879 ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-09-04 13:06 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2019-09-03 14:29 [PATCH 0/2] KVM: Only use posted interrupts for Fixes/LowPrio MSIs Alexander Graf 2019-09-03 14:29 ` [PATCH 1/2] KVM: VMX: Disable posted interrupts for odd IRQs Alexander Graf 2019-09-03 23:15 ` Liran Alon 2019-09-03 14:29 ` [PATCH 2/2] KVM: SVM: " Alexander Graf 2019-09-03 23:20 ` Liran Alon 2019-09-04 13:06 ` Alexander Graf
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