linux-kernel - Re: [PATCH v4 51/75] x86/sev-es: Handle MMIO events

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Date:   Wed, 22 Jul 2020 22:53:02 +0000
From:   Mike Stunes <mstunes@...are.com>
To:     Joerg Roedel <jroedel@...e.de>
CC:     Joerg Roedel <joro@...tes.org>, "x86@...nel.org" <x86@...nel.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        "hpa@...or.com" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        David Rientjes <rientjes@...gle.com>,
        Cfir Cohen <cfir@...gle.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Martin Radev <martin.b.radev@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>
Subject: Re: [PATCH v4 51/75] x86/sev-es: Handle MMIO events



> On Jul 22, 2020, at 1:05 AM, Joerg Roedel <jroedel@...e.de> wrote:
> 
> Hmm, I have a theory ...
> 
> On Tue, Jul 21, 2020 at 09:01:44PM +0000, Mike Stunes wrote:
>> If I remove the call to probe_roms from setup_arch, or remove the calls to romchecksum from probe_roms, this kernel boots normally.
>> 
>> Please let me know of other tests I should run or data that I can collect. Thanks!
> 
> ... can you please try the attached diff?
> 
> diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
> index 251d0aabc55a..e1fea7a38019 100644
> --- a/arch/x86/kernel/sev-es.c
> +++ b/arch/x86/kernel/sev-es.c
> @@ -389,7 +389,8 @@ static bool vc_slow_virt_to_phys(struct ghcb *ghcb, struct es_em_ctxt *ctxt,
> 	pgd_t *pgd;
> 	pte_t *pte;
> 
> -	pgd = pgd_offset(current->active_mm, va);
> +	pgd = __va(read_cr3_pa());
> +	pgd = &pgd[pgd_index(va)];
> 	pte = lookup_address_in_pgd(pgd, va, &level);
> 	if (!pte) {
> 		ctxt->fi.vector     = X86_TRAP_PF;

Thanks Joerg! With that change in place, this kernel boots normally. What was the problem?