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* [PATCH MANUALSEL 5.15 1/8] KVM: X86: Fix tlb flush for tdp in kvm_invalidate_pcid()
@ 2021-11-23 16:36 Sasha Levin
  2021-11-23 16:36 ` [PATCH MANUALSEL 5.15 2/8] KVM: X86: Don't reset mmu context when X86_CR4_PCIDE 1->0 Sasha Levin
                   ` (5 more replies)
  0 siblings, 6 replies; 8+ messages in thread
From: Sasha Levin @ 2021-11-23 16:36 UTC (permalink / raw)
  To: linux-kernel, stable
  Cc: Lai Jiangshan, Paolo Bonzini, Sasha Levin, tglx, mingo, bp,
	dave.hansen, x86, kvm

From: Lai Jiangshan <laijs@linux.alibaba.com>

[ Upstream commit e45e9e3998f0001079b09555db5bb3b4257f6746 ]

The KVM doesn't know whether any TLB for a specific pcid is cached in
the CPU when tdp is enabled.  So it is better to flush all the guest
TLB when invalidating any single PCID context.

The case is very rare or even impossible since KVM generally doesn't
intercept CR3 write or INVPCID instructions when tdp is enabled, so the
fix is mostly for the sake of overall robustness.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211019110154.4091-2-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kvm/x86.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c48e2b5729c5d..0644f429f848c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1091,6 +1091,18 @@ static void kvm_invalidate_pcid(struct kvm_vcpu *vcpu, unsigned long pcid)
 	unsigned long roots_to_free = 0;
 	int i;
 
+	/*
+	 * MOV CR3 and INVPCID are usually not intercepted when using TDP, but
+	 * this is reachable when running EPT=1 and unrestricted_guest=0,  and
+	 * also via the emulator.  KVM's TDP page tables are not in the scope of
+	 * the invalidation, but the guest's TLB entries need to be flushed as
+	 * the CPU may have cached entries in its TLB for the target PCID.
+	 */
+	if (unlikely(tdp_enabled)) {
+		kvm_make_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu);
+		return;
+	}
+
 	/*
 	 * If neither the current CR3 nor any of the prev_roots use the given
 	 * PCID, then nothing needs to be done here because a resync will
-- 
2.33.0


^ permalink raw reply related	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2021-11-24 18:20 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-11-23 16:36 [PATCH MANUALSEL 5.15 1/8] KVM: X86: Fix tlb flush for tdp in kvm_invalidate_pcid() Sasha Levin
2021-11-23 16:36 ` [PATCH MANUALSEL 5.15 2/8] KVM: X86: Don't reset mmu context when X86_CR4_PCIDE 1->0 Sasha Levin
2021-11-24  0:24   ` Lai Jiangshan
2021-11-23 16:36 ` [PATCH MANUALSEL 5.15 3/8] KVM: X86: Don't check unsync if the original spte is writible Sasha Levin
2021-11-23 16:36 ` [PATCH MANUALSEL 5.15 4/8] KVM: selftests: Fix kvm_vm_free() in cr4_cpuid_sync and vmx_tsc_adjust tests Sasha Levin
2021-11-23 16:36 ` [PATCH MANUALSEL 5.15 5/8] KVM: s390: Cap KVM_CAP_NR_VCPUS by num_online_cpus() Sasha Levin
2021-11-23 16:36 ` [PATCH MANUALSEL 5.15 7/8] KVM: MIPS: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS Sasha Levin
2021-11-24 18:20 ` [PATCH MANUALSEL 5.15 1/8] KVM: X86: Fix tlb flush for tdp in kvm_invalidate_pcid() Paolo Bonzini

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