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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, "Denis V. Lunev" <den@openvz.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 10/35] KVM: x86: reinstate vendor-agnostic check on SPEC_CTRL cpuid bits
Date: Mon,  4 Jan 2021 16:57:13 +0100	[thread overview]
Message-ID: <20210104155703.901508760@linuxfoundation.org> (raw)
In-Reply-To: <20210104155703.375788488@linuxfoundation.org>

From: Paolo Bonzini <pbonzini@redhat.com>

[ Upstream commit 39485ed95d6b83b62fa75c06c2c4d33992e0d971 ]

Until commit e7c587da1252 ("x86/speculation: Use synthetic bits for
IBRS/IBPB/STIBP"), KVM was testing both Intel and AMD CPUID bits before
allowing the guest to write MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD.
Testing only Intel bits on VMX processors, or only AMD bits on SVM
processors, fails if the guests are created with the "opposite" vendor
as the host.

While at it, also tweak the host CPU check to use the vendor-agnostic
feature bit X86_FEATURE_IBPB, since we only care about the availability
of the MSR on the host here and not about specific CPUID bits.

Fixes: e7c587da1252 ("x86/speculation: Use synthetic bits for IBRS/IBPB/STIBP")
Cc: stable@vger.kernel.org
Reported-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kvm/cpuid.h | 14 ++++++++++++++
 arch/x86/kvm/svm.c   | 13 +++----------
 arch/x86/kvm/vmx.c   |  6 +++---
 3 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index d78a61408243f..7dec43b2c4205 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -154,6 +154,20 @@ static inline int guest_cpuid_stepping(struct kvm_vcpu *vcpu)
 	return x86_stepping(best->eax);
 }
 
+static inline bool guest_has_spec_ctrl_msr(struct kvm_vcpu *vcpu)
+{
+	return (guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) ||
+		guest_cpuid_has(vcpu, X86_FEATURE_AMD_STIBP) ||
+		guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS) ||
+		guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD));
+}
+
+static inline bool guest_has_pred_cmd_msr(struct kvm_vcpu *vcpu)
+{
+	return (guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) ||
+		guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBPB));
+}
+
 static inline bool supports_cpuid_fault(struct kvm_vcpu *vcpu)
 {
 	return vcpu->arch.msr_platform_info & MSR_PLATFORM_INFO_CPUID_FAULT;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index f513110983d4c..d2dc734f5bd0d 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4209,10 +4209,7 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		break;
 	case MSR_IA32_SPEC_CTRL:
 		if (!msr_info->host_initiated &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_AMD_STIBP) &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS) &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD))
+		    !guest_has_spec_ctrl_msr(vcpu))
 			return 1;
 
 		msr_info->data = svm->spec_ctrl;
@@ -4314,10 +4311,7 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
 		break;
 	case MSR_IA32_SPEC_CTRL:
 		if (!msr->host_initiated &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_AMD_STIBP) &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS) &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD))
+		    !guest_has_spec_ctrl_msr(vcpu))
 			return 1;
 
 		/* The STIBP bit doesn't fault even if it's not advertised */
@@ -4344,12 +4338,11 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
 		break;
 	case MSR_IA32_PRED_CMD:
 		if (!msr->host_initiated &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBPB))
+		    !guest_has_pred_cmd_msr(vcpu))
 			return 1;
 
 		if (data & ~PRED_CMD_IBPB)
 			return 1;
-
 		if (!data)
 			break;
 
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index d6bcbce6c15cb..77b9ed5223f37 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4066,7 +4066,7 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		return kvm_get_msr_common(vcpu, msr_info);
 	case MSR_IA32_SPEC_CTRL:
 		if (!msr_info->host_initiated &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))
+		    !guest_has_spec_ctrl_msr(vcpu))
 			return 1;
 
 		msr_info->data = to_vmx(vcpu)->spec_ctrl;
@@ -4180,7 +4180,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		break;
 	case MSR_IA32_SPEC_CTRL:
 		if (!msr_info->host_initiated &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))
+		    !guest_has_spec_ctrl_msr(vcpu))
 			return 1;
 
 		/* The STIBP bit doesn't fault even if it's not advertised */
@@ -4210,7 +4210,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		break;
 	case MSR_IA32_PRED_CMD:
 		if (!msr_info->host_initiated &&
-		    !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))
+		    !guest_has_pred_cmd_msr(vcpu))
 			return 1;
 
 		if (data & ~PRED_CMD_IBPB)
-- 
2.27.0




  parent reply	other threads:[~2021-01-04 15:59 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-04 15:57 [PATCH 4.19 00/35] 4.19.165-rc1 review Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 01/35] md/raid10: initialize r10_bio->read_slot before use Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 02/35] fscrypt: add fscrypt_is_nokey_name() Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 03/35] ext4: prevent creating duplicate encrypted filenames Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 04/35] f2fs: " Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 05/35] ubifs: " Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 06/35] vfio/pci: Move dummy_resources_list init in vfio_pci_probe() Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 07/35] ext4: dont remount read-only with errors=continue on reboot Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 08/35] uapi: move constants from <linux/kernel.h> to <linux/const.h> Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 09/35] KVM: SVM: relax conditions for allowing MSR_IA32_SPEC_CTRL accesses Greg Kroah-Hartman
2021-01-04 15:57 ` Greg Kroah-Hartman [this message]
2021-01-04 15:57 ` [PATCH 4.19 11/35] powerpc/bitops: Fix possible undefined behaviour with fls() and fls64() Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 12/35] xen/gntdev.c: Mark pages as dirty Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 13/35] null_blk: Fix zone size initialization Greg Kroah-Hartman
2021-01-06 12:54   ` Pavel Machek
2021-01-11  2:46     ` Damien Le Moal
2021-01-04 15:57 ` [PATCH 4.19 14/35] of: fix linker-section match-table corruption Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 15/35] asm-generic/tlb: Track freeing of page-table directories in struct mmu_gather Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 16/35] asm-generic/tlb: Track which levels of the page tables have been cleared Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 17/35] asm-generic/tlb, arch: Invert CONFIG_HAVE_RCU_TABLE_INVALIDATE Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 18/35] powerpc/mmu_gather: enable RCU_TABLE_FREE even for !SMP case Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 19/35] mm/mmu_gather: invalidate TLB correctly on batch allocation failure and flush Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 20/35] asm-generic/tlb: avoid potential double flush Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 21/35] Bluetooth: hci_h5: close serdev device and free hu in h5_close Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 22/35] reiserfs: add check for an invalid ih_entry_count Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 23/35] misc: vmw_vmci: fix kernel info-leak by initializing dbells in vmci_ctx_get_chkpt_doorbells() Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 24/35] media: gp8psk: initialize stats at power control logic Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 25/35] ALSA: seq: Use bool for snd_seq_queue internal flags Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 26/35] ALSA: rawmidi: Access runtime->avail always in spinlock Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 27/35] fcntl: Fix potential deadlock in send_sig{io, urg}() Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 28/35] rtc: sun6i: Fix memleak in sun6i_rtc_clk_init Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 29/35] module: set MODULE_STATE_GOING state when a module fails to load Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 30/35] quota: Dont overflow quota file offsets Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 31/35] powerpc: sysdev: add missing iounmap() on error in mpic_msgr_probe() Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 32/35] NFSv4: Fix a pNFS layout related use-after-free race when freeing the inode Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 33/35] module: delay kobject uevent until after module init call Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 34/35] ALSA: pcm: Clear the full allocated memory at hw_params Greg Kroah-Hartman
2021-01-04 15:57 ` [PATCH 4.19 35/35] dm verity: skip verity work if I/O error when system is shutting down Greg Kroah-Hartman
2021-01-04 17:43 ` [PATCH 4.19 00/35] 4.19.165-rc1 review Daniel Díaz
2021-01-05  9:06   ` Greg Kroah-Hartman
2021-01-04 19:59 ` Pavel Machek
2021-01-04 21:09 ` Jon Hunter
2021-01-05  1:58 ` Guenter Roeck
2021-01-05  9:06   ` Greg Kroah-Hartman
2021-01-05 16:44 ` Shuah Khan
2021-01-06 13:46   ` Greg Kroah-Hartman

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