This is a note to let you know that I've just added the patch titled
KVM: VMX: Introduce vmx_msr_bitmap_l01_changed() helper
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-vmx-introduce-vmx_msr_bitmap_l01_changed-helper.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b84155c38076b36d625043a06a2f1c90bde62903 Mon Sep 17 00:00:00 2001
From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Date: Mon, 29 Nov 2021 10:47:02 +0100
Subject: KVM: VMX: Introduce vmx_msr_bitmap_l01_changed() helper
From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
commit b84155c38076b36d625043a06a2f1c90bde62903 upstream.
In preparation to enabling 'Enlightened MSR Bitmap' feature for Hyper-V
guests move MSR bitmap update tracking to a dedicated helper.
Note: vmx_msr_bitmap_l01_changed() is called when MSR bitmap might be
updated. KVM doesn't check if the bit we're trying to set is already set
(or the bit it's trying to clear is already cleared). Such situations
should not be common and a few false positives should not be a problem.
No functional change intended.
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20211129094704.326635-3-vkuznets@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/vmx/vmx.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3785,6 +3785,17 @@ static void vmx_set_msr_bitmap_write(ulo
__set_bit(msr & 0x1fff, msr_bitmap + 0xc00 / f);
}
+static void vmx_msr_bitmap_l01_changed(struct vcpu_vmx *vmx)
+{
+ /*
+ * When KVM is a nested hypervisor on top of Hyper-V and uses
+ * 'Enlightened MSR Bitmap' feature L0 needs to know that MSR
+ * bitmap has changed.
+ */
+ if (static_branch_unlikely(&enable_evmcs))
+ evmcs_touch_msr_bitmap();
+}
+
static __always_inline void vmx_disable_intercept_for_msr(struct kvm_vcpu *vcpu,
u32 msr, int type)
{
@@ -3794,8 +3805,7 @@ static __always_inline void vmx_disable_
if (!cpu_has_vmx_msr_bitmap())
return;
- if (static_branch_unlikely(&enable_evmcs))
- evmcs_touch_msr_bitmap();
+ vmx_msr_bitmap_l01_changed(vmx);
/*
* Mark the desired intercept state in shadow bitmap, this is needed
@@ -3840,8 +3850,7 @@ static __always_inline void vmx_enable_i
if (!cpu_has_vmx_msr_bitmap())
return;
- if (static_branch_unlikely(&enable_evmcs))
- evmcs_touch_msr_bitmap();
+ vmx_msr_bitmap_l01_changed(vmx);
/*
* Mark the desired intercept state in shadow bitmap, this is needed
Patches currently in stable-queue which might be from vkuznets@xxxxxxxxxx are
queue-5.10/kvm-vmx-introduce-vmx_msr_bitmap_l01_changed-helper.patch
queue-5.10/kvm-nvmx-don-t-use-enlightened-msr-bitmap-for-l3.patch
