[PATCH 2/5] KVM: Clear vcpu->run->flags at start of KVM_RUN for all architectures

[Sean Christopherson]

Clear kvm_run.flags at the start of KVM_RUN for all architectures to
minimize the probability of leaving a stale flag set.

Signed-off-by: Sean Christopherson <sea...@google.com>
---
 arch/arm64/kvm/arm.c         | 1 -
 arch/arm64/kvm/handle_exit.c | 2 +-
 arch/powerpc/kvm/book3s_hv.c | 4 +---
 arch/x86/kvm/x86.c           | 1 -
 virt/kvm/kvm_main.c          | 3 +++
 5 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index a102c3aebdbc..925fa010bb7b 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1128,7 +1128,6 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
        ret = 1;
        run->exit_reason = KVM_EXIT_UNKNOWN;
-       run->flags = 0;
        while (ret > 0) {
                /*
                 * Check conditions before entering the guest
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index d7c2990e7c9e..63692c254a07 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -186,7 +186,7 @@ static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu)
        run->exit_reason = KVM_EXIT_DEBUG;
        run->debug.arch.hsr = lower_32_bits(esr);
        run->debug.arch.hsr_high = upper_32_bits(esr);
-       run->flags = KVM_DEBUG_ARCH_HSR_HIGH_VALID;
+       run->flags |= KVM_DEBUG_ARCH_HSR_HIGH_VALID;
 
        switch (ESR_ELx_EC(esr)) {
        case ESR_ELx_EC_WATCHPT_LOW:
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 25429905ae90..b253f7372774 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -1704,9 +1704,7 @@ static int kvmppc_handle_exit_hv(struct kvm_vcpu *vcpu,
                /* Exit to guest with KVM_EXIT_NMI as exit reason */
                run->exit_reason = KVM_EXIT_NMI;
                run->hw.hardware_exit_reason = vcpu->arch.trap;
-               /* Clear out the old NMI status from run->flags */
-               run->flags &= ~KVM_RUN_PPC_NMI_DISP_MASK;
-               /* Now set the NMI status */
+               /* Note, run->flags is cleared at the start of KVM_RUN. */
                if (vcpu->arch.mce_evt.disposition == MCE_DISPOSITION_RECOVERED)
                        run->flags |= KVM_RUN_PPC_NMI_DISP_FULLY_RECOV;
                else
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1b04092ec76a..a8aa12e0911d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11465,7 +11465,6 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
        vcpu_load(vcpu);
        kvm_sigset_activate(vcpu);
-       kvm_run->flags = 0;
        kvm_load_guest_fpu(vcpu);
 
        kvm_vcpu_srcu_read_lock(vcpu);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index de2c11dae231..7d2076439081 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4336,6 +4336,9 @@ static long kvm_vcpu_ioctl(struct file *filp,
 
                        put_pid(oldpid);
                }
+
+               vcpu->run->flags = 0;
+
                vcpu->wants_to_run = 
!READ_ONCE(vcpu->run->immediate_exit__unsafe);
                r = kvm_arch_vcpu_ioctl_run(vcpu);
                vcpu->wants_to_run = false;
-- 
2.47.1.613.gc27f4b7a9f-goog