linux-kernel - [PATCH v4 06/18] KVM: arm64: nv: Allow coarse-grained trap combos to use complex traps

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Message-ID: <20241025182354.3364124-7-oliver.upton@linux.dev>
Date: Fri, 25 Oct 2024 18:23:41 +0000
From: Oliver Upton <oliver.upton@...ux.dev>
To: kvmarm@...ts.linux.dev
Cc: Marc Zyngier <maz@...nel.org>,
	Joey Gouly <joey.gouly@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Anshuman Khandual <anshuman.khandual@....com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Oliver Upton <oliver.upton@...ux.dev>
Subject: [PATCH v4 06/18] KVM: arm64: nv: Allow coarse-grained trap combos to use complex traps

KVM uses a sanity-check to avoid infinite recursion in trap combinations
that could potentially depend on itself. Narrow the scope of this sanity
check to the exact CGT IDs that correspond w/ trap combos, opening the
door to using 'complex' traps as part of a combination.

Signed-off-by: Oliver Upton <oliver.upton@...ux.dev>
---
 arch/arm64/kvm/emulate-nested.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
index 05b6435d02a9..da7ab14e036d 100644
--- a/arch/arm64/kvm/emulate-nested.c
+++ b/arch/arm64/kvm/emulate-nested.c
@@ -2021,7 +2021,8 @@ int __init populate_nv_trap_config(void)
 		cgids = coarse_control_combo[id - __MULTIPLE_CONTROL_BITS__];
 
 		for (int i = 0; cgids[i] != __RESERVED__; i++) {
-			if (cgids[i] >= __MULTIPLE_CONTROL_BITS__) {
+			if (cgids[i] >= __MULTIPLE_CONTROL_BITS__ &&
+			    cgids[i] < __COMPLEX_CONDITIONS__) {
 				kvm_err("Recursive MCB %d/%d\n", id, cgids[i]);
 				ret = -EINVAL;
 			}
-- 
2.47.0.163.g1226f6d8fa-goog