Thread (120 messages) 120 messages, 6 authors, 2026-01-13
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[PATCH v2 14/45] KVM: arm64: Use kernel-space partid configuration for hypercalls

From: Ben Horgan <ben.horgan@arm.com>
Date: 2025-12-19 18:13:09
Also in: kvmarm, lkml
Subsystem: arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers: Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds

On nVHE systems whether or not MPAM is enabled, EL2 continues to use
partid-0 for hypercalls, even when the host may have configured its kernel
threads to use a different partid. 0 may have been assigned to another
task. Copy the EL1 MPAM register to EL2. This ensures hypercalls use the
same partid as the kernel thread does on the host.

Signed-off-by: Ben Horgan <ben.horgan@arm.com>
---
 arch/arm64/kvm/hyp/nvhe/hyp-main.c | 5 +++++
 1 file changed, 5 insertions(+)
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index a7c689152f68..5c1de7e7dd38 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -635,6 +635,11 @@ static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)
 	unsigned long hcall_min = 0;
 	hcall_t hfn;
 
+	if (system_supports_mpam()) {
+		write_sysreg_s(read_sysreg_s(SYS_MPAM1_EL1), SYS_MPAM2_EL2);
+		isb();
+	}
+
 	/*
 	 * If pKVM has been initialised then reject any calls to the
 	 * early "privileged" hypercalls. Note that we cannot reject
-- 
2.43.0

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