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Subject: Re: [PATCH] kdump, vmcoreinfo: Export sme_me_mask value to vmcoreinfo
To:     Borislav Petkov <bp@alien8.de>
Cc:     Baoquan He <bhe@redhat.com>, Petr Tesarik <ptesarik@suse.cz>,
        linux-kernel@vger.kernel.org, x86@kernel.org,
        kexec@lists.infradead.org, mingo@redhat.com, tglx@linutronix.de,
        dyoung@redhat.com
References: <20181027091007.GB1046@nazgul.tnic>
 <20181027093917.GA14493@MiWiFi-R3L-srv> <20181027101221.GC1046@nazgul.tnic>
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 <c55bef2a-b972-7e6e-b698-6ac1bc736046@redhat.com>
 <20181027145151.GA7338@nazgul.tnic>
 <390b16ba-05d7-3590-c3b2-4b69aa3ae051@redhat.com>
 <20181029083118.GC1884@MiWiFi-R3L-srv>
 <d6f93848-c750-f29c-4ca7-9661596cad62@redhat.com>
 <20181029095738.GB20101@zn.tnic>
From:   lijiang <lijiang@redhat.com>
Message-ID: <15897206-c1a6-ced6-3a1b-f71da8fc9c83@redhat.com>
Date:   Mon, 29 Oct 2018 18:12:19 +0800
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在 2018年10月29日 17:57, Borislav Petkov 写道:
> On Mon, Oct 29, 2018 at 05:29:16PM +0800, lijiang wrote:
>> Ok, i will change it to a local variable and export it.
> 
> Why do you have to export it at all?!
> 

I mean that i will write the value of local variable to the vmcoreinfo. For example:

diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 4c8acdfdc5a7..3cc975e7ff8f 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -352,11 +352,16 @@ void machine_kexec(struct kimage *image)

 void arch_crash_save_vmcoreinfo(void)
 {
+       u64 sme_mask = 0;
+
        VMCOREINFO_NUMBER(phys_base);
        VMCOREINFO_SYMBOL(init_top_pgt);
        vmcoreinfo_append_str("NUMBER(pgtable_l5_enabled)=%d\n",
                        pgtable_l5_enabled());

+       sme_mask = sme_me_mask;
+       VMCOREINFO_NUMBER(sme_mask);
+
 #ifdef CONFIG_NUMA
        VMCOREINFO_SYMBOL(node_data);
        VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
-- 


Because the crash kernel's page table(pgd/pud/pmd/pte) contains
the memory encryption mask(bit 47), makedumpfile needs to remove
the sme mask to obtain the true physical address.


Thanks.
Lianbo