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Message-Id: <20210315135551.658870954@linuxfoundation.org>
Date: Mon, 15 Mar 2021 15:22:35 +0100
From: gregkh@...uxfoundation.org
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Marc Zyngier <maz@...nel.org>,
Will Deacon <will@...nel.org>,
Catalin Marinas <catalin.marinas@....com>
Subject: [PATCH 5.10 285/290] KVM: arm64: Ensure I-cache isolation between vcpus of a same VM
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
From: Marc Zyngier <maz@...nel.org>
Commit 01dc9262ff5797b675c32c0c6bc682777d23de05 upstream.
It recently became apparent that the ARMv8 architecture has interesting
rules regarding attributes being used when fetching instructions
if the MMU is off at Stage-1.
In this situation, the CPU is allowed to fetch from the PoC and
allocate into the I-cache (unless the memory is mapped with
the XN attribute at Stage-2).
If we transpose this to vcpus sharing a single physical CPU,
it is possible for a vcpu running with its MMU off to influence
another vcpu running with its MMU on, as the latter is expected to
fetch from the PoU (and self-patching code doesn't flush below that
level).
In order to solve this, reuse the vcpu-private TLB invalidation
code to apply the same policy to the I-cache, nuking it every time
the vcpu runs on a physical CPU that ran another vcpu of the same
VM in the past.
This involve renaming __kvm_tlb_flush_local_vmid() to
__kvm_flush_cpu_context(), and inserting a local i-cache invalidation
there.
Cc: stable@...r.kernel.org
Signed-off-by: Marc Zyngier <maz@...nel.org>
Acked-by: Will Deacon <will@...nel.org>
Acked-by: Catalin Marinas <catalin.marinas@....com>
Link: https://lore.kernel.org/r/20210303164505.68492-1-maz@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
arch/arm64/include/asm/kvm_asm.h | 4 ++--
arch/arm64/kvm/arm.c | 7 ++++++-
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 4 ++--
arch/arm64/kvm/hyp/nvhe/tlb.c | 3 ++-
arch/arm64/kvm/hyp/vhe/tlb.c | 3 ++-
5 files changed, 14 insertions(+), 7 deletions(-)
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -49,7 +49,7 @@
#define __KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context 2
#define __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid_ipa 3
#define __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid 4
-#define __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_local_vmid 5
+#define __KVM_HOST_SMCCC_FUNC___kvm_flush_cpu_context 5
#define __KVM_HOST_SMCCC_FUNC___kvm_timer_set_cntvoff 6
#define __KVM_HOST_SMCCC_FUNC___kvm_enable_ssbs 7
#define __KVM_HOST_SMCCC_FUNC___vgic_v3_get_ich_vtr_el2 8
@@ -180,10 +180,10 @@ DECLARE_KVM_HYP_SYM(__bp_harden_hyp_vecs
#define __bp_harden_hyp_vecs CHOOSE_HYP_SYM(__bp_harden_hyp_vecs)
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(struct kvm_s2_mmu *mmu);
-extern void __kvm_tlb_flush_local_vmid(struct kvm_s2_mmu *mmu);
extern void __kvm_timer_set_cntvoff(u64 cntvoff);
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -352,11 +352,16 @@ void kvm_arch_vcpu_load(struct kvm_vcpu
last_ran = this_cpu_ptr(mmu->last_vcpu_ran);
/*
+ * We guarantee that both TLBs and I-cache are private to each
+ * vcpu. If detecting that a vcpu from the same VM has
+ * previously run on the same physical CPU, call into the
+ * hypervisor code to nuke the relevant contexts.
+ *
* We might get preempted before the vCPU actually runs, but
* over-invalidation doesn't affect correctness.
*/
if (*last_ran != vcpu->vcpu_id) {
- kvm_call_hyp(__kvm_tlb_flush_local_vmid, mmu);
+ kvm_call_hyp(__kvm_flush_cpu_context, mmu);
*last_ran = vcpu->vcpu_id;
}
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -46,11 +46,11 @@ static void handle_host_hcall(unsigned l
__kvm_tlb_flush_vmid(kern_hyp_va(mmu));
break;
}
- case KVM_HOST_SMCCC_FUNC(__kvm_tlb_flush_local_vmid): {
+ case KVM_HOST_SMCCC_FUNC(__kvm_flush_cpu_context): {
unsigned long r1 = host_ctxt->regs.regs[1];
struct kvm_s2_mmu *mmu = (struct kvm_s2_mmu *)r1;
- __kvm_tlb_flush_local_vmid(kern_hyp_va(mmu));
+ __kvm_flush_cpu_context(kern_hyp_va(mmu));
break;
}
case KVM_HOST_SMCCC_FUNC(__kvm_timer_set_cntvoff): {
--- a/arch/arm64/kvm/hyp/nvhe/tlb.c
+++ b/arch/arm64/kvm/hyp/nvhe/tlb.c
@@ -123,7 +123,7 @@ void __kvm_tlb_flush_vmid(struct kvm_s2_
__tlb_switch_to_host(&cxt);
}
-void __kvm_tlb_flush_local_vmid(struct kvm_s2_mmu *mmu)
+void __kvm_flush_cpu_context(struct kvm_s2_mmu *mmu)
{
struct tlb_inv_context cxt;
@@ -131,6 +131,7 @@ void __kvm_tlb_flush_local_vmid(struct k
__tlb_switch_to_guest(mmu, &cxt);
__tlbi(vmalle1);
+ asm volatile("ic iallu");
dsb(nsh);
isb();
--- a/arch/arm64/kvm/hyp/vhe/tlb.c
+++ b/arch/arm64/kvm/hyp/vhe/tlb.c
@@ -127,7 +127,7 @@ void __kvm_tlb_flush_vmid(struct kvm_s2_
__tlb_switch_to_host(&cxt);
}
-void __kvm_tlb_flush_local_vmid(struct kvm_s2_mmu *mmu)
+void __kvm_flush_cpu_context(struct kvm_s2_mmu *mmu)
{
struct tlb_inv_context cxt;
@@ -135,6 +135,7 @@ void __kvm_tlb_flush_local_vmid(struct k
__tlb_switch_to_guest(mmu, &cxt);
__tlbi(vmalle1);
+ asm volatile("ic iallu");
dsb(nsh);
isb();
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