From: Jim Mattson <jmattson@google.com>
To: kvm@vger.kernel.org, "'Sean Christopherson '" <seanjc@google.com>,
"'Paolo Bonzini '" <pbonzini@redhat.com>
Cc: Jim Mattson <jmattson@google.com>
Subject: [PATCH v4 2/3] KVM: x86: Virtualize HWCR.TscFreqSel[bit 24]
Date: Fri, 29 Sep 2023 16:02:45 -0700 [thread overview]
Message-ID: <20230929230246.1954854-3-jmattson@google.com> (raw)
In-Reply-To: <20230929230246.1954854-1-jmattson@google.com>
On certain CPUs, Linux guests expect HWCR.TscFreqSel[bit 24] to be
set. If it isn't set, they complain:
[Firmware Bug]: TSC doesn't count with P0 frequency!
Allow userspace to set this bit in the virtual HWCR to eliminate the
above complaint.
Signed-off-by: Jim Mattson <jmattson@google.com>
---
arch/x86/kvm/x86.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1a323cae219c..86a1bb0e6227 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3700,8 +3700,12 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
data &= ~(u64)0x100; /* ignore ignne emulation enable */
data &= ~(u64)0x8; /* ignore TLB cache disable */
- /* Handle McStatusWrEn */
- if (data & ~BIT_ULL(18)) {
+ /*
+ * Allow McStatusWrEn and TscFreqSel. (Linux guests from v3.2
+ * through at least v6.6 whine if TscFreqSel is clear,
+ * depending on F/M/S.
+ */
+ if (data & ~(BIT_ULL(18) | BIT_ULL(24))) {
kvm_pr_unimpl_wrmsr(vcpu, msr, data);
return 1;
}
--
2.42.0.582.g8ccd20d70d-goog
next prev parent reply other threads:[~2023-09-29 23:02 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-29 23:02 [PATCH v4 0/3] KVM: x86: Update HWCR virtualization Jim Mattson
2023-09-29 23:02 ` [PATCH v4 1/3] KVM: x86: Allow HWCR.McStatusWrEn to be cleared once set Jim Mattson
2023-09-29 23:02 ` Jim Mattson [this message]
2023-09-29 23:02 ` [PATCH v4 3/3] KVM: selftests: Test behavior of HWCR Jim Mattson
2023-10-06 3:44 ` Sean Christopherson
2023-10-06 3:59 ` Jim Mattson
2023-10-09 20:05 ` [PATCH v4 0/3] KVM: x86: Update HWCR virtualization Sean Christopherson
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