From 4288ff7ba195f49138eec0d9c4ff8c049714e918 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <maz@kernel.org>
Date: Wed, 18 Oct 2023 23:32:09 +0000
Subject: [PATCH] KVM: arm64: Restore the stage-2 context in VHE's
__tlb_switch_to_host()
An MMU notifier could cause us to clobber the stage-2 context loaded on
a CPU when we switch to another VM's context to invalidate. This isn't
an issue right now as the stage-2 context gets reloaded on every guest
entry, but is disastrous when moving __load_stage2() into the
vcpu_load() path.
Restore the previous stage-2 context on the way out of a TLB
invalidation if we installed something else. Deliberately do this after
TGE=1 is synchronized to keep things safe in light of the speculative AT
errata.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231018233212.2888027-3-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
arch/arm64/kvm/hyp/vhe/tlb.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kvm/hyp/vhe/tlb.c b/arch/arm64/kvm/hyp/vhe/tlb.c
index f3f2e142e4f44..b636b4111dbf5 100644
--- a/arch/arm64/kvm/hyp/vhe/tlb.c
+++ b/arch/arm64/kvm/hyp/vhe/tlb.c
@@ -11,18 +11,25 @@
#include <asm/tlbflush.h>
struct tlb_inv_context {
- unsigned long flags;
- u64 tcr;
- u64 sctlr;
+ struct kvm_s2_mmu *mmu;
+ unsigned long flags;
+ u64 tcr;
+ u64 sctlr;
};
static void __tlb_switch_to_guest(struct kvm_s2_mmu *mmu,
struct tlb_inv_context *cxt)
{
+ struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
u64 val;
local_irq_save(cxt->flags);
+ if (vcpu && mmu != vcpu->arch.hw_mmu)
+ cxt->mmu = vcpu->arch.hw_mmu;
+ else
+ cxt->mmu = NULL;
+
if (cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT)) {
/*
* For CPUs that are affected by ARM errata 1165522 or 1530923,
@@ -69,6 +76,10 @@ static void __tlb_switch_to_host(struct tlb_inv_context *cxt)
write_sysreg(HCR_HOST_VHE_FLAGS, hcr_el2);
isb();
+ /* ... and the stage-2 MMU context that we switched away from */
+ if (cxt->mmu)
+ __load_stage2(cxt->mmu, cxt->mmu->arch);
+
if (cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT)) {
/* Restore the registers to what they were */
write_sysreg_el1(cxt->tcr, SYS_TCR);
--
2.30.2