[PATCH v3 3/5] KVM: arm64: pkvm: Document the side effects of kvm_flush_dcache_to_poc()
Marc Zyngier
maz at kernel.org
Thu Apr 13 01:14:39 PDT 2023
We rely on the presence of a DSB at the end of kvm_flush_dcache_to_poc()
that, on top of ensuring completion of the cache clean, also covers
the speculative page table walk started from EL1.
Document this dependency.
Signed-off-by: Marc Zyngier <maz at kernel.org>
Reviewed-by: Oliver Upton <oliver.upton at linux.dev>
---
arch/arm64/kvm/hyp/nvhe/mem_protect.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 552653fa18be..2e9ec4a2a4a3 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -297,6 +297,13 @@ int __pkvm_prot_finalize(void)
params->vttbr = kvm_get_vttbr(mmu);
params->vtcr = host_mmu.arch.vtcr;
params->hcr_el2 |= HCR_VM;
+
+ /*
+ * The CMO below not only cleans the updated params to the
+ * PoC, but also provides the DSB that ensures ongoing
+ * page-table walks that have started before we trapped to EL2
+ * have completed.
+ */
kvm_flush_dcache_to_poc(params, sizeof(*params));
write_sysreg(params->hcr_el2, hcr_el2);
--
2.34.1
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