From: Krish Sadhukhan <krish.sadhukhan@oracle.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: vkuznets@redhat.com, sean.j.christopherson@intel.com
Subject: Re: [PATCH] KVM: nVMX: remove side effects from nested_vmx_exit_reflected
Date: Thu, 19 Mar 2020 13:11:14 -0700 [thread overview]
Message-ID: <4aa41614-51f0-7e4f-57b6-0e15329036a5@oracle.com> (raw)
In-Reply-To: <1584468059-3585-1-git-send-email-pbonzini@redhat.com>
On 3/17/20 11:00 AM, Paolo Bonzini wrote:
> The name of nested_vmx_exit_reflected suggests that it's purely
> a test, but it actually marks VMCS12 pages as dirty. Move this to
> vmx_handle_exit, observing that the initial nested_run_pending check in
> nested_vmx_exit_reflected is pointless---nested_run_pending has just
> been cleared in vmx_vcpu_run and won't be set until handle_vmlaunch
> or handle_vmresume.
>
> Suggested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> arch/x86/kvm/vmx/nested.c | 18 ++----------------
> arch/x86/kvm/vmx/nested.h | 1 +
> arch/x86/kvm/vmx/vmx.c | 19 +++++++++++++++++--
> 3 files changed, 20 insertions(+), 18 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 8578513907d7..4ff859c99946 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -3527,7 +3527,7 @@ static void vmcs12_save_pending_event(struct kvm_vcpu *vcpu,
> }
>
>
> -static void nested_mark_vmcs12_pages_dirty(struct kvm_vcpu *vcpu)
> +void nested_mark_vmcs12_pages_dirty(struct kvm_vcpu *vcpu)
> {
> struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
> gfn_t gfn;
> @@ -5543,8 +5543,7 @@ bool nested_vmx_exit_reflected(struct kvm_vcpu *vcpu, u32 exit_reason)
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
>
> - if (vmx->nested.nested_run_pending)
> - return false;
> + WARN_ON_ONCE(vmx->nested.nested_run_pending);
>
> if (unlikely(vmx->fail)) {
> trace_kvm_nested_vmenter_failed(
> @@ -5553,19 +5552,6 @@ bool nested_vmx_exit_reflected(struct kvm_vcpu *vcpu, u32 exit_reason)
> return true;
> }
>
> - /*
> - * The host physical addresses of some pages of guest memory
> - * are loaded into the vmcs02 (e.g. vmcs12's Virtual APIC
> - * Page). The CPU may write to these pages via their host
> - * physical address while L2 is running, bypassing any
> - * address-translation-based dirty tracking (e.g. EPT write
> - * protection).
> - *
> - * Mark them dirty on every exit from L2 to prevent them from
> - * getting out of sync with dirty tracking.
> - */
> - nested_mark_vmcs12_pages_dirty(vcpu);
> -
> trace_kvm_nested_vmexit(kvm_rip_read(vcpu), exit_reason,
> vmcs_readl(EXIT_QUALIFICATION),
> vmx->idt_vectoring_info,
> diff --git a/arch/x86/kvm/vmx/nested.h b/arch/x86/kvm/vmx/nested.h
> index 21d36652f213..f70968b76d33 100644
> --- a/arch/x86/kvm/vmx/nested.h
> +++ b/arch/x86/kvm/vmx/nested.h
> @@ -33,6 +33,7 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
> int get_vmx_mem_address(struct kvm_vcpu *vcpu, unsigned long exit_qualification,
> u32 vmx_instruction_info, bool wr, int len, gva_t *ret);
> void nested_vmx_pmu_entry_exit_ctls_update(struct kvm_vcpu *vcpu);
> +void nested_mark_vmcs12_pages_dirty(struct kvm_vcpu *vcpu);
> bool nested_vmx_check_io_bitmaps(struct kvm_vcpu *vcpu, unsigned int port,
> int size);
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index b447d66f44e6..07299a957d4a 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -5851,8 +5851,23 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu,
> if (vmx->emulation_required)
> return handle_invalid_guest_state(vcpu);
>
> - if (is_guest_mode(vcpu) && nested_vmx_exit_reflected(vcpu, exit_reason))
> - return nested_vmx_reflect_vmexit(vcpu, exit_reason);
> + if (is_guest_mode(vcpu)) {
> + /*
> + * The host physical addresses of some pages of guest memory
> + * are loaded into the vmcs02 (e.g. vmcs12's Virtual APIC
> + * Page). The CPU may write to these pages via their host
> + * physical address while L2 is running, bypassing any
> + * address-translation-based dirty tracking (e.g. EPT write
> + * protection).
> + *
> + * Mark them dirty on every exit from L2 to prevent them from
> + * getting out of sync with dirty tracking.
> + */
> + nested_mark_vmcs12_pages_dirty(vcpu);
> +
> + if (nested_vmx_exit_reflected(vcpu, exit_reason))
> + return nested_vmx_reflect_vmexit(vcpu, exit_reason);
> + }
>
> if (exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY) {
> dump_vmcs();
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
prev parent reply other threads:[~2020-03-19 20:11 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-17 18:00 [PATCH] KVM: nVMX: remove side effects from nested_vmx_exit_reflected Paolo Bonzini
2020-03-18 10:52 ` Vitaly Kuznetsov
2020-03-18 10:59 ` Paolo Bonzini
2020-03-18 15:12 ` Sean Christopherson
2020-03-19 20:11 ` Krish Sadhukhan [this message]
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=4aa41614-51f0-7e4f-57b6-0e15329036a5@oracle.com \
--to=krish.sadhukhan@oracle.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=sean.j.christopherson@intel.com \
--cc=vkuznets@redhat.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).