Currently, checks for whether VT-d PI can be used refer to the current
status of the feature in the current vCPU; or they more or less pick
vCPU 0 in case a specific vCPU is not available.
However, these checks do not attempt to synchronize with changes to
the IRTE. In particular, there is no path that updates the IRTE when
APICv is re-activated on vCPU 0; and there is no path to wakeup a CPU
that has APICv disabled, if the wakeup occurs because of an IRTE
that points to a posted interrupt.
To fix this, always go through the VT-d PI path as long as there are
assigned devices and APICv is available on both the host and the VM side.
Since the relevant condition was copied over three times, take the hint
and factor it into a separate function.
Suggested-by: Sean Christopherson <seanjc(a)google.com>
Cc: stable(a)vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com>
---
arch/x86/kvm/vmx/posted_intr.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c
index 5f81ef092bd4..b64dd1374ed9 100644
--- a/arch/x86/kvm/vmx/posted_intr.c
+++ b/arch/x86/kvm/vmx/posted_intr.c
@@ -5,6 +5,7 @@
#include <asm/cpu.h>
#include "lapic.h"
+#include "irq.h"
#include "posted_intr.h"
#include "trace.h"
#include "vmx.h"
@@ -77,13 +78,18 @@ void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)
pi_set_on(pi_desc);
}
+static bool vmx_can_use_vtd_pi(struct kvm *kvm)
+{
+ return kvm_arch_has_assigned_device(kvm) &&
+ irq_remapping_cap(IRQ_POSTING_CAP) &&
+ irqchip_in_kernel(kvm) && enable_apicv;
+}
+
void vmx_vcpu_pi_put(struct kvm_vcpu *vcpu)
{
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
- if (!kvm_arch_has_assigned_device(vcpu->kvm) ||
- !irq_remapping_cap(IRQ_POSTING_CAP) ||
- !kvm_vcpu_apicv_active(vcpu))
+ if (!vmx_can_use_vtd_pi(vcpu->kvm))
return;
/* Set SN when the vCPU is preempted */
@@ -141,9 +147,7 @@ int pi_pre_block(struct kvm_vcpu *vcpu)
struct pi_desc old, new;
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
- if (!kvm_arch_has_assigned_device(vcpu->kvm) ||
- !irq_remapping_cap(IRQ_POSTING_CAP) ||
- !kvm_vcpu_apicv_active(vcpu))
+ if (!vmx_can_use_vtd_pi(vcpu->kvm))
return 0;
WARN_ON(irqs_disabled());
@@ -270,9 +274,7 @@ int pi_update_irte(struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq,
struct vcpu_data vcpu_info;
int idx, ret = 0;
- if (!kvm_arch_has_assigned_device(kvm) ||
- !irq_remapping_cap(IRQ_POSTING_CAP) ||
- !kvm_vcpu_apicv_active(kvm->vcpus[0]))
+ if (!vmx_can_use_vtd_pi(kvm))
return 0;
idx = srcu_read_lock(&kvm->irq_srcu);
--
2.27.0
Commit 4f86a06e2d6e ("irqdomain: Make normal and nomap irqdomains
exclusive") introduced an IRQ_DOMAIN_FLAG_NO_MAP flag to isolate the
'nomap' domains still in use under the powerpc arch. With this new
flag, the revmap_tree of the IRQ domain is not used anymore. This
change broke the support of shared LSIs [1] in the XIVE driver because
it was relying on a lookup in the revmap_tree to query previously
mapped interrupts. Linux now creates two distinct IRQ mappings on the
same HW IRQ which can lead to unexpected behavior in the drivers.
The XIVE IRQ domain is not a direct mapping domain and its HW IRQ
interrupt number space is rather large : 1M/socket on POWER9 and
POWER10, change the XIVE driver to use a 'tree' domain type instead.
[1] For instance, a linux KVM guest with virtio-rng and virtio-balloon
devices.
Cc: Marc Zyngier <maz(a)kernel.org>
Cc: stable(a)vger.kernel.org # v5.14+
Fixes: 4f86a06e2d6e ("irqdomain: Make normal and nomap irqdomains exclusive")
Signed-off-by: Cédric Le Goater <clg(a)kaod.org>
---
Marc,
The Fixes tag is there because the patch in question revealed that
something was broken in XIVE. genirq is not in cause. However, I
don't know for PS3 and Cell. May be less critical for now.
arch/powerpc/sysdev/xive/common.c | 3 +--
arch/powerpc/sysdev/xive/Kconfig | 1 -
2 files changed, 1 insertion(+), 3 deletions(-)
diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
index fed6fd16c8f4..9d0f0fe25598 100644
--- a/arch/powerpc/sysdev/xive/common.c
+++ b/arch/powerpc/sysdev/xive/common.c
@@ -1536,8 +1536,7 @@ static const struct irq_domain_ops xive_irq_domain_ops = {
static void __init xive_init_host(struct device_node *np)
{
- xive_irq_domain = irq_domain_add_nomap(np, XIVE_MAX_IRQ,
- &xive_irq_domain_ops, NULL);
+ xive_irq_domain = irq_domain_add_tree(np, &xive_irq_domain_ops, NULL);
if (WARN_ON(xive_irq_domain == NULL))
return;
irq_set_default_host(xive_irq_domain);
diff --git a/arch/powerpc/sysdev/xive/Kconfig b/arch/powerpc/sysdev/xive/Kconfig
index 97796c6b63f0..785c292d104b 100644
--- a/arch/powerpc/sysdev/xive/Kconfig
+++ b/arch/powerpc/sysdev/xive/Kconfig
@@ -3,7 +3,6 @@ config PPC_XIVE
bool
select PPC_SMP_MUXED_IPI
select HARDIRQS_SW_RESEND
- select IRQ_DOMAIN_NOMAP
config PPC_XIVE_NATIVE
bool
--
2.31.1