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Message-Id: <20191219183211.803963252@linuxfoundation.org>
Date: Thu, 19 Dec 2019 19:32:53 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Jim Mattson <jmattson@...gle.com>,
Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 4.4 065/162] KVM: x86: fix presentation of TSX feature in ARCH_CAPABILITIES
From: Paolo Bonzini <pbonzini@...hat.com>
commit cbbaa2727aa3ae9e0a844803da7cef7fd3b94f2b upstream.
KVM does not implement MSR_IA32_TSX_CTRL, so it must not be presented
to the guests. It is also confusing to have !ARCH_CAP_TSX_CTRL_MSR &&
!RTM && ARCH_CAP_TAA_NO: lack of MSR_IA32_TSX_CTRL suggests TSX was not
hidden (it actually was), yet the value says that TSX is not vulnerable
to microarchitectural data sampling. Fix both.
Cc: stable@...r.kernel.org
Tested-by: Jim Mattson <jmattson@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
arch/x86/kvm/x86.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1024,10 +1024,15 @@ u64 kvm_get_arch_capabilities(void)
* If TSX is disabled on the system, guests are also mitigated against
* TAA and clear CPU buffer mitigation is not required for guests.
*/
- if (boot_cpu_has_bug(X86_BUG_TAA) && boot_cpu_has(X86_FEATURE_RTM) &&
- (data & ARCH_CAP_TSX_CTRL_MSR))
+ if (!boot_cpu_has(X86_FEATURE_RTM))
+ data &= ~ARCH_CAP_TAA_NO;
+ else if (!boot_cpu_has_bug(X86_BUG_TAA))
+ data |= ARCH_CAP_TAA_NO;
+ else if (data & ARCH_CAP_TSX_CTRL_MSR)
data &= ~ARCH_CAP_MDS_NO;
+ /* KVM does not emulate MSR_IA32_TSX_CTRL. */
+ data &= ~ARCH_CAP_TSX_CTRL_MSR;
return data;
}
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