Commit 1702da76 authored by Vincent Donnefort's avatar Vincent Donnefort Committed by Marc Zyngier
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KVM: arm64: Fix nVHE/pKVM hyp tracing error on invalid desc 



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: default avatarVincent Donnefort <vdonnefort@google.com>
Fixes: 680a04c3 ("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: default avatarMarc Zyngier <maz@kernel.org>
parent f19c354d

arch/arm64/kvm/hyp/nvhe/trace.c

+7 −2
Original line number Diff line number Diff line
@@ -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);