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Message-Id: <20211009021236.4122790-5-seanjc@google.com>
Date: Fri, 8 Oct 2021 19:11:57 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Huacai Chen <chenhuacai@...nel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
Paul Mackerras <paulus@...abs.org>,
Anup Patel <anup.patel@....com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Christian Borntraeger <borntraeger@...ibm.com>,
Janosch Frank <frankja@...ux.ibm.com>,
Paolo Bonzini <pbonzini@...hat.com>
Cc: James Morse <james.morse@....com>,
Alexandru Elisei <alexandru.elisei@....com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Atish Patra <atish.patra@....com>,
David Hildenbrand <david@...hat.com>,
Cornelia Huck <cohuck@...hat.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>,
Sean Christopherson <seanjc@...gle.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>,
linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
linux-mips@...r.kernel.org, kvm@...r.kernel.org,
kvm-ppc@...r.kernel.org, kvm-riscv@...ts.infradead.org,
linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
David Matlack <dmatlack@...gle.com>,
Oliver Upton <oupton@...gle.com>,
Jing Zhang <jingzhangos@...gle.com>
Subject: [PATCH v2 04/43] KVM: Force PPC to define its own rcuwait object
Do not define/reference kvm_vcpu.wait if __KVM_HAVE_ARCH_WQP is true, and
instead force the architecture (PPC) to define its own rcuwait object.
Allowing common KVM to directly access vcpu->wait without a guard makes
it all too easy to introduce potential bugs, e.g. kvm_vcpu_block(),
kvm_vcpu_on_spin(), and async_pf_execute() all operate on vcpu->wait, not
the result of kvm_arch_vcpu_get_wait(), and so may do the wrong thing for
PPC.
Due to PPC's shenanigans with respect to callbacks and waits (it switches
to the virtual core's wait object at KVM_RUN!?!?), it's not clear whether
or not this fixes any bugs.
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
arch/powerpc/include/asm/kvm_host.h | 1 +
arch/powerpc/kvm/powerpc.c | 3 ++-
include/linux/kvm_host.h | 2 ++
virt/kvm/async_pf.c | 2 +-
virt/kvm/kvm_main.c | 9 ++++++---
5 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 59cb38b04ede..876c10803cda 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -749,6 +749,7 @@ struct kvm_vcpu_arch {
u8 irq_pending; /* Used by XIVE to signal pending guest irqs */
u32 last_inst;
+ struct rcuwait wait;
struct rcuwait *waitp;
struct kvmppc_vcore *vcore;
int ret;
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 8ab90ce8738f..be22da157569 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -762,7 +762,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
if (err)
goto out_vcpu_uninit;
- vcpu->arch.waitp = &vcpu->wait;
+ rcuwait_init(&vcpu->arch.wait);
+ vcpu->arch.waitp = &vcpu->arch.wait;
kvmppc_create_vcpu_debugfs(vcpu, vcpu->vcpu_id);
return 0;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 60a35d9fe259..1ced2914d9ca 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -310,7 +310,9 @@ struct kvm_vcpu {
struct mutex mutex;
struct kvm_run *run;
+#ifndef __KVM_HAVE_ARCH_WQP
struct rcuwait wait;
+#endif
struct pid __rcu *pid;
int sigset_active;
sigset_t sigset;
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index dd777688d14a..ccb35c22785e 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -85,7 +85,7 @@ static void async_pf_execute(struct work_struct *work)
trace_kvm_async_pf_completed(addr, cr2_or_gpa);
- rcuwait_wake_up(&vcpu->wait);
+ rcuwait_wake_up(kvm_arch_vcpu_get_wait(vcpu));
mmput(mm);
kvm_put_kvm(vcpu->kvm);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7bc38549487e..5d4a90032277 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -421,7 +421,9 @@ static void kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
vcpu->kvm = kvm;
vcpu->vcpu_id = id;
vcpu->pid = NULL;
+#ifndef __KVM_HAVE_ARCH_WQP
rcuwait_init(&vcpu->wait);
+#endif
kvm_async_pf_vcpu_init(vcpu);
vcpu->pre_pcpu = -1;
@@ -3213,6 +3215,7 @@ update_halt_poll_stats(struct kvm_vcpu *vcpu, u64 poll_ns, bool waited)
*/
void kvm_vcpu_block(struct kvm_vcpu *vcpu)
{
+ struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);
bool halt_poll_allowed = !kvm_arch_no_poll(vcpu);
ktime_t start, cur, poll_end;
bool waited = false;
@@ -3251,7 +3254,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
}
- prepare_to_rcuwait(&vcpu->wait);
+ prepare_to_rcuwait(wait);
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
@@ -3261,7 +3264,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
waited = true;
schedule();
}
- finish_rcuwait(&vcpu->wait);
+ finish_rcuwait(wait);
cur = ktime_get();
if (waited) {
vcpu->stat.generic.halt_wait_ns +=
@@ -3460,7 +3463,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me, bool yield_to_kernel_mode)
continue;
if (vcpu == me)
continue;
- if (rcuwait_active(&vcpu->wait) &&
+ if (rcuwait_active(kvm_arch_vcpu_get_wait(vcpu)) &&
!vcpu_dy_runnable(vcpu))
continue;
if (READ_ONCE(vcpu->preempted) && yield_to_kernel_mode &&
--
2.33.0.882.g93a45727a2-goog
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