From: Peter Xu <peterx@redhat.com>
To: Alexander Graf <graf@amazon.com>
Cc: kvm list <kvm@vger.kernel.org>,
Aaron Lewis <aaronlewis@google.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
KarimAllah Raslan <karahmed@amazon.de>,
Dan Carpenter <dan.carpenter@oracle.com>,
Maxim Levitsky <mlevitsk@redhat.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v8 6/8] KVM: x86: VMX: Prevent MSR passthrough when MSR access is denied
Date: Thu, 1 Oct 2020 21:11:39 -0400 [thread overview]
Message-ID: <20201002011139.GA5473@xz-x1> (raw)
In-Reply-To: <20200925143422.21718-7-graf@amazon.com>
Hi,
I reported in the v13 cover letter of kvm dirty ring series that this patch
seems to have been broken. Today I tried to reproduce with a simplest vm, and
after a closer look...
On Fri, Sep 25, 2020 at 04:34:20PM +0200, Alexander Graf wrote:
> @@ -3764,15 +3859,14 @@ static u8 vmx_msr_bitmap_mode(struct kvm_vcpu *vcpu)
> return mode;
> }
>
> -static void vmx_update_msr_bitmap_x2apic(struct kvm_vcpu *vcpu,
> - unsigned long *msr_bitmap, u8 mode)
> +static void vmx_update_msr_bitmap_x2apic(struct kvm_vcpu *vcpu, u8 mode)
> {
> int msr;
>
> - for (msr = 0x800; msr <= 0x8ff; msr += BITS_PER_LONG) {
> - unsigned word = msr / BITS_PER_LONG;
> - msr_bitmap[word] = (mode & MSR_BITMAP_MODE_X2APIC_APICV) ? 0 : ~0;
> - msr_bitmap[word + (0x800 / sizeof(long))] = ~0;
> + for (msr = 0x800; msr <= 0x8ff; msr++) {
> + bool intercepted = !!(mode & MSR_BITMAP_MODE_X2APIC_APICV);
> +
> + vmx_set_intercept_for_msr(vcpu, msr, MSR_TYPE_RW, intercepted);
> }
>
> if (mode & MSR_BITMAP_MODE_X2APIC) {
... I think we may want below change to be squashed:
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d160aad59697..7d3f2815b04d 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3781,9 +3781,10 @@ static void vmx_update_msr_bitmap_x2apic(struct kvm_vcpu *vcpu, u8 mode)
int msr;
for (msr = 0x800; msr <= 0x8ff; msr++) {
- bool intercepted = !!(mode & MSR_BITMAP_MODE_X2APIC_APICV);
+ bool apicv = mode & MSR_BITMAP_MODE_X2APIC_APICV;
- vmx_set_intercept_for_msr(vcpu, msr, MSR_TYPE_RW, intercepted);
+ vmx_set_intercept_for_msr(vcpu, msr, MSR_TYPE_R, !apicv);
+ vmx_set_intercept_for_msr(vcpu, msr, MSR_TYPE_W, true);
}
if (mode & MSR_BITMAP_MODE_X2APIC) {
This fixes my problem the same as having this patch reverted.
--
Peter Xu
next prev parent reply other threads:[~2020-10-02 1:11 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-25 14:34 [PATCH v8 0/8] Allow user space to restrict and augment MSR emulation Alexander Graf
2020-09-25 14:34 ` [PATCH v8 1/8] KVM: x86: Return -ENOENT on unimplemented MSRs Alexander Graf
2020-09-25 16:40 ` Jim Mattson
2020-09-25 14:34 ` [PATCH v8 2/8] KVM: x86: Deflect unknown MSR accesses to user space Alexander Graf
2020-09-28 16:05 ` Aaron Lewis
2020-09-25 14:34 ` [PATCH v8 3/8] KVM: x86: Add infrastructure for MSR filtering Alexander Graf
2020-09-28 16:08 ` Aaron Lewis
2020-09-25 14:34 ` [PATCH v8 4/8] KVM: x86: Prepare MSR bitmaps for userspace tracked MSRs Alexander Graf
2020-09-25 14:34 ` [PATCH v8 5/8] KVM: x86: SVM: Prevent MSR passthrough when MSR access is denied Alexander Graf
2020-09-25 22:01 ` Paolo Bonzini
2020-09-25 22:22 ` Paolo Bonzini
2020-09-25 14:34 ` [PATCH v8 6/8] KVM: x86: VMX: " Alexander Graf
2020-10-02 1:11 ` Peter Xu [this message]
2020-10-05 18:43 ` Sean Christopherson
2020-09-25 14:34 ` [PATCH v8 7/8] KVM: x86: Introduce MSR filtering Alexander Graf
2020-09-28 16:09 ` Aaron Lewis
2020-09-25 14:34 ` [PATCH v8 8/8] KVM: selftests: Add test for user space MSR handling Alexander Graf
2020-09-28 16:10 ` Aaron Lewis
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