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KVM: arm64: Fix nVHE/pKVM hyp tracing error on invalid desc

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pKVM must validate the host-provided tracing buffer descriptor.
However, if an error is found, the hypervisor would just return 0 to the
host. Fix the return value on validation failure.

While at it, rename the function to hyp_trace_desc_is_valid() and skip
validation for the nVHE mode as we trust host-provided data in that
case.

Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Fixes: 680a04c333 ("KVM: arm64: Add tracing capability for the nVHE/pKVM hyp")
Link: https://lore.kernel.org/r/20260514162624.3477857-1-vdonnefort@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Vincent Donnefort 2026-05-14 17:26:24 +01:00 committed by Marc Zyngier
parent f19c354dbd
commit 1702da76e0
1 changed files with 7 additions and 2 deletions
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9
arch/arm64/kvm/hyp/nvhe/trace.c
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@ -164,13 +164,16 @@ static int hyp_trace_buffer_load(struct hyp_trace_buffer *trace_buffer,
return ret;
}
static bool hyp_trace_desc_validate(struct hyp_trace_desc *desc, size_t desc_size)
static bool hyp_trace_desc_is_valid(struct hyp_trace_desc *desc, size_t desc_size)
{
struct ring_buffer_desc *rb_desc;
unsigned int cpu;
size_t nr_bpages;
void *desc_end;
if (!is_protected_kvm_enabled())
return true;
/*
* Both desc_size and bpages_backing_size are untrusted host-provided
* values. We rely on __pkvm_host_donate_hyp() to enforce their validity.
@ -212,8 +215,10 @@ int __tracing_load(unsigned long desc_hva, size_t desc_size)
if (ret)
return ret;
if (!hyp_trace_desc_validate(desc, desc_size))
if (!hyp_trace_desc_is_valid(desc, desc_size)) {
ret = -EINVAL;
goto err_release_desc;
}
hyp_spin_lock(&trace_buffer.lock);