linux-kernel - [PATCH 2/4] KVM: ARM: replace system_event.flags with ndata and data[0]

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Date:   Thu, 21 Apr 2022 14:04:41 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     will@...nel.org, maz@...nel.org, apatel@...tanamicro.com,
        atishp@...osinc.com, seanjc@...gle.com, pgonda@...gle.com
Subject: [PATCH 2/4] KVM: ARM: replace system_event.flags with ndata and data[0]

The flags datum for KVM_EXIT_SYSTEM_EVENT exits has been
removed because it was defined incorrectly; no padding was
introduced between the 32-bit type and the 64-bit flags,
resulting in different definitions for 32-bit and 64-bit
userspace.

The replacement is a pair of fields, ndata and data[],
with ndata saying how many items are valid in the data array.
In the case of ARM that's one, as flags can be simply moved
to data[0].

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/arm64/kvm/psci.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
index baac2b405f23..708d80e8e60d 100644
--- a/arch/arm64/kvm/psci.c
+++ b/arch/arm64/kvm/psci.c
@@ -181,7 +181,8 @@ static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type, u64 flags)
 
 	memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event));
 	vcpu->run->system_event.type = type;
-	vcpu->run->system_event.flags = flags;
+	vcpu->run->system_event.ndata = 1;
+	vcpu->run->system_event.data[0] = flags;
 	vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
 }
 
-- 
2.31.1