From: ilstam@mailbox.org
To: kvm@vger.kernel.org, pbonzini@redhat.com
Cc: ilstam@amazon.com, seanjc@google.com, vkuznets@redhat.com,
wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org,
haozhong.zhang@intel.com, zamsden@gmail.com, mtosatti@redhat.com,
dplotnikov@virtuozzo.com, dwmw@amazon.co.uk
Subject: [PATCH 6/8] KVM: VMX: Make vmx_write_l1_tsc_offset() work with nested TSC scaling
Date: Thu, 6 May 2021 10:32:26 +0000 [thread overview]
Message-ID: <20210506103228.67864-7-ilstam@mailbox.org> (raw)
In-Reply-To: <20210506103228.67864-1-ilstam@mailbox.org>
From: Ilias Stamatis <ilstam@amazon.com>
Calculating the current TSC offset is done differently when nested TSC
scaling is used.
Signed-off-by: Ilias Stamatis <ilstam@amazon.com>
---
arch/x86/kvm/vmx/vmx.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 49241423b854..df7dc0e4c903 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1797,10 +1797,16 @@ static void setup_msrs(struct vcpu_vmx *vmx)
vmx_update_msr_bitmap(&vmx->vcpu);
}
-static u64 vmx_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
+/*
+ * This function receives the requested offset for L1 as an argument but it
+ * actually writes the "current" tsc offset to the VMCS and returns it. The
+ * current offset might be different in case an L2 guest is currently running
+ * and its VMCS02 is loaded.
+ */
+static u64 vmx_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 l1_offset)
{
struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
- u64 g_tsc_offset = 0;
+ u64 cur_offset = l1_offset;
/*
* We're here if L1 chose not to trap WRMSR to TSC. According
@@ -1809,11 +1815,19 @@ static u64 vmx_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
* to the newly set TSC to get L2's TSC.
*/
if (is_guest_mode(vcpu) &&
- (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETTING))
- g_tsc_offset = vmcs12->tsc_offset;
+ (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETTING)) {
+ if (vmcs12->secondary_vm_exec_control & SECONDARY_EXEC_TSC_SCALING) {
+ cur_offset = kvm_compute_02_tsc_offset(
+ l1_offset,
+ vmcs12->tsc_multiplier,
+ vmcs12->tsc_offset);
+ } else {
+ cur_offset = l1_offset + vmcs12->tsc_offset;
+ }
+ }
- vmcs_write64(TSC_OFFSET, offset + g_tsc_offset);
- return offset + g_tsc_offset;
+ vmcs_write64(TSC_OFFSET, cur_offset);
+ return cur_offset;
}
/*
--
2.17.1
next prev parent reply other threads:[~2021-05-06 10:36 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-06 10:32 [PATCH 0/8] KVM: VMX: Implement nested TSC scaling ilstam
2021-05-06 10:32 ` [PATCH 1/8] KVM: VMX: Add a TSC multiplier field in VMCS12 ilstam
2021-05-06 14:50 ` kernel test robot
2021-05-06 17:36 ` Jim Mattson
2021-05-10 13:42 ` Maxim Levitsky
2021-05-06 10:32 ` [PATCH 2/8] KVM: X86: Store L1's TSC scaling ratio in 'struct kvm_vcpu_arch' ilstam
2021-05-10 13:43 ` Maxim Levitsky
2021-05-06 10:32 ` [PATCH 3/8] KVM: X86: Pass an additional 'L1' argument to kvm_scale_tsc() ilstam
2021-05-10 13:52 ` Maxim Levitsky
2021-05-10 15:44 ` Stamatis, Ilias
2021-05-06 10:32 ` [PATCH 4/8] KVM: VMX: Adjust the TSC-related VMCS fields on L2 entry and exit ilstam
2021-05-06 11:32 ` Paolo Bonzini
2021-05-06 17:35 ` Stamatis, Ilias
2021-05-10 14:11 ` Paolo Bonzini
2021-05-10 13:53 ` Maxim Levitsky
2021-05-10 14:44 ` Stamatis, Ilias
2021-05-11 12:38 ` Maxim Levitsky
2021-05-11 15:11 ` Stamatis, Ilias
2021-05-06 10:32 ` [PATCH 5/8] KVM: X86: Move tracing outside write_l1_tsc_offset() ilstam
2021-05-10 13:54 ` Maxim Levitsky
2021-05-06 10:32 ` ilstam [this message]
2021-05-10 13:54 ` [PATCH 6/8] KVM: VMX: Make vmx_write_l1_tsc_offset() work with nested TSC scaling Maxim Levitsky
2021-05-10 16:08 ` Stamatis, Ilias
2021-05-11 12:44 ` Maxim Levitsky
2021-05-11 17:44 ` Stamatis, Ilias
2021-05-06 10:32 ` [PATCH 7/8] KVM: VMX: Expose TSC scaling to L2 ilstam
2021-05-10 13:56 ` Maxim Levitsky
2021-05-06 10:32 ` [PATCH 8/8] KVM: selftests: x86: Add vmx_nested_tsc_scaling_test ilstam
2021-05-10 13:59 ` Maxim Levitsky
2021-05-11 11:16 ` Stamatis, Ilias
2021-05-11 12:47 ` Maxim Levitsky
2021-05-11 14:02 ` Stamatis, Ilias
2021-05-06 17:16 ` [PATCH 0/8] KVM: VMX: Implement nested TSC scaling Jim Mattson
2021-05-06 17:48 ` Stamatis, Ilias
2021-05-10 13:43 ` Maxim Levitsky
2021-05-10 14:29 ` Paolo Bonzini
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