From: Marc Zyngier <maz@xxxxxxxxxx>
Broadcast TLB invalidations (TLBIs) targeting the Inner Shareable
Domain are usually less performant than their non-shareable variant.
In particular, we observed some implementations that take
millliseconds to complete parallel broadcasted TLBIs.
It's safe to use non-shareable TLBIs when relaxing permissions on a
PTE in the KVM case. According to the ARM ARM (0487I.a) section
D8.13.1 "Using break-before-make when updating translation table
entries", permission relaxation does not need break-before-make.
Specifically, R_WHZWS states that these are the only changes that
require a break-before-make sequence: changes of memory type
(Shareability or Cacheability), address changes, or changing the block
size.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Signed-off-by: Ricardo Koller <ricarkol@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_asm.h | 4 +++
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 10 ++++++
arch/arm64/kvm/hyp/nvhe/tlb.c | 54 ++++++++++++++++++++++++++++++
arch/arm64/kvm/hyp/pgtable.c | 2 +-
arch/arm64/kvm/hyp/vhe/tlb.c | 32 ++++++++++++++++++
5 files changed, 101 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 43c3bc0f9544d..bb17b2ead4c71 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -68,6 +68,7 @@ enum __kvm_host_smccc_func {
__KVM_HOST_SMCCC_FUNC___kvm_vcpu_run,
__KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context,
__KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid_ipa,
+ __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid_ipa_nsh,
__KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid,
__KVM_HOST_SMCCC_FUNC___kvm_flush_cpu_context,
__KVM_HOST_SMCCC_FUNC___kvm_timer_set_cntvoff,
@@ -225,6 +226,9 @@ extern void __kvm_flush_vm_context(void);
extern void __kvm_flush_cpu_context(struct kvm_s2_mmu *mmu);
extern void __kvm_tlb_flush_vmid_ipa(struct kvm_s2_mmu *mmu, phys_addr_t ipa,
int level);
+extern void __kvm_tlb_flush_vmid_ipa_nsh(struct kvm_s2_mmu *mmu,
+ phys_addr_t ipa,
+ int level);
extern void __kvm_tlb_flush_vmid(struct kvm_s2_mmu *mmu);
extern void __kvm_timer_set_cntvoff(u64 cntvoff);
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 728e01d4536b0..c6bf1e49ca934 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -125,6 +125,15 @@ static void handle___kvm_tlb_flush_vmid_ipa(struct kvm_cpu_context *host_ctxt)
__kvm_tlb_flush_vmid_ipa(kern_hyp_va(mmu), ipa, level);
}
+static void handle___kvm_tlb_flush_vmid_ipa_nsh(struct kvm_cpu_context *host_ctxt)
+{
+ DECLARE_REG(struct kvm_s2_mmu *, mmu, host_ctxt, 1);
+ DECLARE_REG(phys_addr_t, ipa, host_ctxt, 2);
+ DECLARE_REG(int, level, host_ctxt, 3);
+
+ __kvm_tlb_flush_vmid_ipa_nsh(kern_hyp_va(mmu), ipa, level);
+}
+
static void handle___kvm_tlb_flush_vmid(struct kvm_cpu_context *host_ctxt)
{
DECLARE_REG(struct kvm_s2_mmu *, mmu, host_ctxt, 1);
@@ -315,6 +324,7 @@ static const hcall_t host_hcall[] = {
HANDLE_FUNC(__kvm_vcpu_run),
HANDLE_FUNC(__kvm_flush_vm_context),
HANDLE_FUNC(__kvm_tlb_flush_vmid_ipa),
+ HANDLE_FUNC(__kvm_tlb_flush_vmid_ipa_nsh),
HANDLE_FUNC(__kvm_tlb_flush_vmid),
HANDLE_FUNC(__kvm_flush_cpu_context),
HANDLE_FUNC(__kvm_timer_set_cntvoff),
diff --git a/arch/arm64/kvm/hyp/nvhe/tlb.c b/arch/arm64/kvm/hyp/nvhe/tlb.c
index d296d617f5896..ef2b70587f933 100644
--- a/arch/arm64/kvm/hyp/nvhe/tlb.c
+++ b/arch/arm64/kvm/hyp/nvhe/tlb.c
@@ -109,6 +109,60 @@ void __kvm_tlb_flush_vmid_ipa(struct kvm_s2_mmu *mmu,
__tlb_switch_to_host(&cxt);
}
+void __kvm_tlb_flush_vmid_ipa_nsh(struct kvm_s2_mmu *mmu,
+ phys_addr_t ipa, int level)
+{
+ struct tlb_inv_context cxt;
+
+ dsb(nshst);
+
+ /* Switch to requested VMID */
+ __tlb_switch_to_guest(mmu, &cxt);
+
+ /*
+ * We could do so much better if we had the VA as well.
+ * Instead, we invalidate Stage-2 for this IPA, and the
+ * whole of Stage-1. Weep...
+ */
+ ipa >>= 12;
+ __tlbi_level(ipas2e1, ipa, level);
+
+ /*
+ * We have to ensure completion of the invalidation at Stage-2,
+ * since a table walk on another CPU could refill a TLB with a
+ * complete (S1 + S2) walk based on the old Stage-2 mapping if
+ * the Stage-1 invalidation happened first.
+ */
+ dsb(nsh);
+ __tlbi(vmalle1);
+ dsb(nsh);
+ isb();
+
+ /*
+ * If the host is running at EL1 and we have a VPIPT I-cache,
+ * then we must perform I-cache maintenance at EL2 in order for
+ * it to have an effect on the guest. Since the guest cannot hit
+ * I-cache lines allocated with a different VMID, we don't need
+ * to worry about junk out of guest reset (we nuke the I-cache on
+ * VMID rollover), but we do need to be careful when remapping
+ * executable pages for the same guest. This can happen when KSM
+ * takes a CoW fault on an executable page, copies the page into
+ * a page that was previously mapped in the guest and then needs
+ * to invalidate the guest view of the I-cache for that page
+ * from EL1. To solve this, we invalidate the entire I-cache when
+ * unmapping a page from a guest if we have a VPIPT I-cache but
+ * the host is running at EL1. As above, we could do better if
+ * we had the VA.
+ *
+ * The moral of this story is: if you have a VPIPT I-cache, then
+ * you should be running with VHE enabled.
+ */
+ if (icache_is_vpipt())
+ icache_inval_all_pou();
+
+ __tlb_switch_to_host(&cxt);
+}
+
void __kvm_tlb_flush_vmid(struct kvm_s2_mmu *mmu)
{
struct tlb_inv_context cxt;
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 48c5a95c6e8cd..023269dd84f76 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1189,7 +1189,7 @@ int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr,
KVM_PGTABLE_WALK_HANDLE_FAULT |
KVM_PGTABLE_WALK_SHARED);
if (!ret)
- kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, pgt->mmu, addr, level);
+ kvm_call_hyp(__kvm_tlb_flush_vmid_ipa_nsh, pgt->mmu, addr, level);
return ret;
}
diff --git a/arch/arm64/kvm/hyp/vhe/tlb.c b/arch/arm64/kvm/hyp/vhe/tlb.c
index 24cef9b87f9e9..e69da550cdc5b 100644
--- a/arch/arm64/kvm/hyp/vhe/tlb.c
+++ b/arch/arm64/kvm/hyp/vhe/tlb.c
@@ -111,6 +111,38 @@ void __kvm_tlb_flush_vmid_ipa(struct kvm_s2_mmu *mmu,
__tlb_switch_to_host(&cxt);
}
+void __kvm_tlb_flush_vmid_ipa_nsh(struct kvm_s2_mmu *mmu,
+ phys_addr_t ipa, int level)
+{
+ struct tlb_inv_context cxt;
+
+ dsb(nshst);
+
+ /* Switch to requested VMID */
+ __tlb_switch_to_guest(mmu, &cxt);
+
+ /*
+ * We could do so much better if we had the VA as well.
+ * Instead, we invalidate Stage-2 for this IPA, and the
+ * whole of Stage-1. Weep...
+ */
+ ipa >>= 12;
+ __tlbi_level(ipas2e1, ipa, level);
+
+ /*
+ * We have to ensure completion of the invalidation at Stage-2,
+ * since a table walk on another CPU could refill a TLB with a
+ * complete (S1 + S2) walk based on the old Stage-2 mapping if
+ * the Stage-1 invalidation happened first.
+ */
+ dsb(nsh);
+ __tlbi(vmalle1);
+ dsb(nsh);
+ isb();
+
+ __tlb_switch_to_host(&cxt);
+}
+
void __kvm_tlb_flush_vmid(struct kvm_s2_mmu *mmu)
{
struct tlb_inv_context cxt;
--
2.40.0.577.gac1e443424-goog
