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From: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
To: stable@vger.kernel.org
Cc: x86@kernel.org, kvm@vger.kernel.org, bp@alien8.de,
	pbonzini@redhat.com, peterz@infradead.org, jpoimboe@kernel.org
Subject: [PATCH 5.4 29/37] KVM: VMX: Fix IBRS handling after vmexit
Date: Mon,  3 Oct 2022 10:10:30 -0300	[thread overview]
Message-ID: <20221003131038.12645-30-cascardo@canonical.com> (raw)
In-Reply-To: <20221003131038.12645-1-cascardo@canonical.com>

From: Josh Poimboeuf <jpoimboe@kernel.org>

commit bea7e31a5caccb6fe8ed989c065072354f0ecb52 upstream.

For legacy IBRS to work, the IBRS bit needs to be always re-written
after vmexit, even if it's already on.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
---
 arch/x86/kvm/vmx/vmx.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 85d5dfb261f5..d522c9de41df 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6571,8 +6571,13 @@ void noinstr vmx_spec_ctrl_restore_host(struct vcpu_vmx *vmx,
 
 	/*
 	 * If the guest/host SPEC_CTRL values differ, restore the host value.
+	 *
+	 * For legacy IBRS, the IBRS bit always needs to be written after
+	 * transitioning from a less privileged predictor mode, regardless of
+	 * whether the guest/host values differ.
 	 */
-	if (vmx->spec_ctrl != hostval)
+	if (cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS) ||
+	    vmx->spec_ctrl != hostval)
 		native_wrmsrl(MSR_IA32_SPEC_CTRL, hostval);
 
 	barrier_nospec();
-- 
2.34.1


  parent reply	other threads:[~2022-10-03 13:13 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-03 13:10 [PATCH 5.4 00/37] IBRS support // Retbleed mitigations Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 01/37] Revert "x86/speculation: Add RSB VM Exit protections" Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 02/37] Revert "x86/cpu: Add a steppings field to struct x86_cpu_id" Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 03/37] x86/devicetable: Move x86 specific macro out of generic code Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 04/37] x86/cpu: Add consistent CPU match macros Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 05/37] x86/cpu: Add a steppings field to struct x86_cpu_id Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 06/37] x86/kvm/vmx: Make noinstr clean Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 07/37] x86/cpufeatures: Move RETPOLINE flags to word 11 Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 08/37] x86/bugs: Report AMD retbleed vulnerability Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 09/37] x86/bugs: Add AMD retbleed= boot parameter Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 10/37] x86/bugs: Keep a per-CPU IA32_SPEC_CTRL value Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 11/37] x86/entry: Remove skip_r11rcx Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 12/37] x86/entry: Add kernel IBRS implementation Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 13/37] x86/bugs: Optimize SPEC_CTRL MSR writes Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 14/37] x86/speculation: Add spectre_v2=ibrs option to support Kernel IBRS Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 15/37] x86/bugs: Split spectre_v2_select_mitigation() and spectre_v2_user_select_mitigation() Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 16/37] x86/bugs: Report Intel retbleed vulnerability Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 17/37] intel_idle: Disable IBRS during long idle Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 18/37] x86/speculation: Change FILL_RETURN_BUFFER to work with objtool Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 19/37] x86/speculation: Fix RSB filling with CONFIG_RETPOLINE=n Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 20/37] x86/speculation: Fix firmware entry SPEC_CTRL handling Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 21/37] x86/speculation: Fix SPEC_CTRL write on SMT state change Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 22/37] x86/speculation: Use cached host SPEC_CTRL value for guest entry/exit Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 23/37] x86/speculation: Remove x86_spec_ctrl_mask Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 24/37] KVM/VMX: Use TEST %REG,%REG instead of CMP $0,%REG in vmenter.S Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 25/37] KVM/nVMX: Use __vmx_vcpu_run in nested_vmx_check_vmentry_hw Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 26/37] KVM: VMX: Flatten __vmx_vcpu_run() Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 27/37] KVM: VMX: Convert launched argument to flags Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 28/37] KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` Thadeu Lima de Souza Cascardo [this message]
2022-10-03 13:10 ` [PATCH 5.4 30/37] x86/speculation: Fill RSB on vmexit for IBRS Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 31/37] x86/common: Stamp out the stepping madness Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 32/37] x86/cpu/amd: Enumerate BTC_NO Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 33/37] x86/bugs: Add Cannon lake to RETBleed affected CPU list Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 34/37] x86/speculation: Disable RRSBA behavior Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 35/37] x86/speculation: Use DECLARE_PER_CPU for x86_spec_ctrl_current Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 36/37] x86/bugs: Warn when "ibrs" mitigation is selected on Enhanced IBRS parts Thadeu Lima de Souza Cascardo
2022-10-03 13:10 ` [PATCH 5.4 37/37] x86/speculation: Add RSB VM Exit protections Thadeu Lima de Souza Cascardo
2022-10-05 10:34 ` [PATCH 5.4 00/37] IBRS support // Retbleed mitigations Greg KH

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