kvm.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
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


  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 " 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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210506103228.67864-7-ilstam@mailbox.org \
    --to=ilstam@mailbox.org \
    --cc=dplotnikov@virtuozzo.com \
    --cc=dwmw@amazon.co.uk \
    --cc=haozhong.zhang@intel.com \
    --cc=ilstam@amazon.com \
    --cc=jmattson@google.com \
    --cc=joro@8bytes.org \
    --cc=kvm@vger.kernel.org \
    --cc=mtosatti@redhat.com \
    --cc=pbonzini@redhat.com \
    --cc=seanjc@google.com \
    --cc=vkuznets@redhat.com \
    --cc=wanpengli@tencent.com \
    --cc=zamsden@gmail.com \
    --subject='Re: [PATCH 6/8] KVM: VMX: Make vmx_write_l1_tsc_offset() work with nested TSC scaling' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).