From: Sean Christopherson <seanjc@google.com>
To: David Edmondson <david.edmondson@oracle.com>
Cc: linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Joerg Roedel <joro@8bytes.org>,
x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Ingo Molnar <mingo@redhat.com>, Jim Mattson <jmattson@google.com>,
Borislav Petkov <bp@alien8.de>,
Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH v2 1/3] KVM: x86: dump_vmcs should not assume GUEST_IA32_EFER is valid
Date: Tue, 23 Feb 2021 14:51:19 -0800 [thread overview]
Message-ID: <YDWG51Io0VJEBHGg@google.com> (raw)
In-Reply-To: <20210219144632.2288189-2-david.edmondson@oracle.com>
On Fri, Feb 19, 2021, David Edmondson wrote:
> If the VM entry/exit controls for loading/saving MSR_EFER are either
> not available (an older processor or explicitly disabled) or not
> used (host and guest values are the same), reading GUEST_IA32_EFER
> from the VMCS returns an inaccurate value.
>
> Because of this, in dump_vmcs() don't use GUEST_IA32_EFER to decide
> whether to print the PDPTRs - do so if the EPT is in use and CR4.PAE
> is set.
This isn't necessarily correct either. In a way, it's less correct as PDPTRs
are more likely to be printed when they shouldn't, assuming most guests are
64-bit guests. It's annoying to calculate the effective guest EFER, but so
awful that it's worth risking confusion over PDTPRs.
> Fixes: 4eb64dce8d0a ("KVM: x86: dump VMCS on invalid entry")
> Signed-off-by: David Edmondson <david.edmondson@oracle.com>
> ---
> arch/x86/kvm/vmx/vmx.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index eb69fef57485..818051c9fa10 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -5759,7 +5759,6 @@ void dump_vmcs(void)
> u32 vmentry_ctl, vmexit_ctl;
> u32 cpu_based_exec_ctrl, pin_based_exec_ctrl, secondary_exec_control;
> unsigned long cr4;
> - u64 efer;
>
> if (!dump_invalid_vmcs) {
> pr_warn_ratelimited("set kvm_intel.dump_invalid_vmcs=1 to dump internal KVM state.\n");
> @@ -5771,7 +5770,6 @@ void dump_vmcs(void)
> cpu_based_exec_ctrl = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
> pin_based_exec_ctrl = vmcs_read32(PIN_BASED_VM_EXEC_CONTROL);
> cr4 = vmcs_readl(GUEST_CR4);
> - efer = vmcs_read64(GUEST_IA32_EFER);
> secondary_exec_control = 0;
> if (cpu_has_secondary_exec_ctrls())
> secondary_exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
> @@ -5784,8 +5782,7 @@ void dump_vmcs(void)
> cr4, vmcs_readl(CR4_READ_SHADOW), vmcs_readl(CR4_GUEST_HOST_MASK));
> pr_err("CR3 = 0x%016lx\n", vmcs_readl(GUEST_CR3));
> if ((secondary_exec_control & SECONDARY_EXEC_ENABLE_EPT) &&
> - (cr4 & X86_CR4_PAE) && !(efer & EFER_LMA))
> - {
> + (cr4 & X86_CR4_PAE)) {
> pr_err("PDPTR0 = 0x%016llx PDPTR1 = 0x%016llx\n",
> vmcs_read64(GUEST_PDPTR0), vmcs_read64(GUEST_PDPTR1));
> pr_err("PDPTR2 = 0x%016llx PDPTR3 = 0x%016llx\n",
> @@ -5811,7 +5808,8 @@ void dump_vmcs(void)
> if ((vmexit_ctl & (VM_EXIT_SAVE_IA32_PAT | VM_EXIT_SAVE_IA32_EFER)) ||
> (vmentry_ctl & (VM_ENTRY_LOAD_IA32_PAT | VM_ENTRY_LOAD_IA32_EFER)))
> pr_err("EFER = 0x%016llx PAT = 0x%016llx\n",
> - efer, vmcs_read64(GUEST_IA32_PAT));
> + vmcs_read64(GUEST_IA32_EFER),
> + vmcs_read64(GUEST_IA32_PAT));
> pr_err("DebugCtl = 0x%016llx DebugExceptions = 0x%016lx\n",
> vmcs_read64(GUEST_IA32_DEBUGCTL),
> vmcs_readl(GUEST_PENDING_DBG_EXCEPTIONS));
> --
> 2.30.0
>
next prev parent reply other threads:[~2021-02-23 23:01 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-19 14:46 [PATCH v2 0/3] KVM: x86: dump_vmcs: don't assume GUEST_IA32_EFER, show MSR autoloads/autosaves David Edmondson
2021-02-19 14:46 ` [PATCH v2 1/3] KVM: x86: dump_vmcs should not assume GUEST_IA32_EFER is valid David Edmondson
2021-02-23 22:51 ` Sean Christopherson [this message]
2021-02-23 23:13 ` Jim Mattson
2021-02-23 23:41 ` Sean Christopherson
2021-02-24 13:30 ` David Edmondson
2021-02-23 23:18 ` Jim Mattson
2021-02-19 14:46 ` [PATCH v2 2/3] KVM: x86: dump_vmcs should not conflate EFER and PAT presence in VMCS David Edmondson
2021-02-23 22:58 ` Sean Christopherson
2021-02-24 13:31 ` David Edmondson
2021-02-19 14:46 ` [PATCH v2 3/3] KVM: x86: dump_vmcs should include the autoload/autostore MSR lists David Edmondson
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=YDWG51Io0VJEBHGg@google.com \
--to=seanjc@google.com \
--cc=bp@alien8.de \
--cc=david.edmondson@oracle.com \
--cc=hpa@zytor.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=pbonzini@redhat.com \
--cc=tglx@linutronix.de \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.com \
--cc=x86@kernel.org \
/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).