Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <83e1eb701804d9d5afdaf2f26574a793f85a0292.camel@redhat.com>
Subject: Re: [PATCH RESEND v4 23/23] KVM: x86: smm: preserve interrupt
 shadow in SMRAM
From:   Maxim Levitsky <mlevitsk@redhat.com>
To:     Paolo Bonzini <pbonzini@redhat.com>, kvm@vger.kernel.org
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Yang Zhong <yang.zhong@intel.com>, x86@kernel.org,
        Jim Mattson <jmattson@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Shuah Khan <shuah@kernel.org>,
        Guang Zeng <guang.zeng@intel.com>,
        Joerg Roedel <joro@8bytes.org>, linux-kernel@vger.kernel.org,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        linux-kselftest@vger.kernel.org, Kees Cook <keescook@chromium.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Wei Wang <wei.w.wang@intel.com>,
        Borislav Petkov <bp@alien8.de>
Date:   Sun, 30 Oct 2022 10:23:42 +0200
In-Reply-To: <137568e8-90a6-19e3-1bcb-055ed0c419e7@redhat.com>
References: <20221025124741.228045-1-mlevitsk@redhat.com>
         <20221025124741.228045-24-mlevitsk@redhat.com>
         <137568e8-90a6-19e3-1bcb-055ed0c419e7@redhat.com>
Content-Type: text/plain; charset="UTF-8"
User-Agent: Evolution 3.40.4 (3.40.4-5.fc34) 
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

On Fri, 2022-10-28 at 12:35 +0200, Paolo Bonzini wrote:
> On 10/25/22 14:47, Maxim Levitsky wrote:
> > @@ -19,7 +19,8 @@ struct kvm_smram_state_32 {
> >         u32 reserved1[62];
> >         u32 smbase;
> >         u32 smm_revision;
> > -       u32 reserved2[5];
> > +       u32 reserved2[4];
> > +       u32 int_shadow; /* KVM extension */
> >         u32 cr4; /* CR4 is not present in Intel/AMD SMRAM image */
> >         u32 reserved3[5];
> 
> Of course the placement of KVM-specific fields is somewhat arbitrary, 
> but based on sandpile.org data I would place it at 0xFF1A ("reserved", 
> you have to search for 7F1Ah in the web page).
> 
> > @@ -86,7 +87,7 @@ struct kvm_smram_state_64 {
> >         u64 io_restart_rsi;
> >         u64 io_restart_rdi;
> >         u32 io_restart_dword;
> > -       u32 reserved1;
> > +       u32 int_shadow;
> >         u8 io_inst_restart;
> >         u8 auto_hlt_restart;
> >         u8 reserved2[6];
> 
> Likewise, based on AMD BKDG I would place this at 0xFECB after the "NMI 
> Mask" field (which unfortunately I learnt about only after "inventing" 
> HF_SMM_INSIDE_NMI_MASK).

I don't see any problem with this, makes sense.

I wish AMD would keep on releaseing the BKDG - I haven't looked there
because last public version is very old.


Thanks!
Best regards,
	Maxim Levitsky

> 
> I can do the changes myself, but please ack.
> 
> Paolo
>