From: Tom Lendacky <thomas.lendacky@amd.com>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ashish Kalra <Ashish.Kalra@amd.com>,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, luto@kernel.org, x86@kernel.org,
ardb@kernel.org, hpa@zytor.com, linux-efi@vger.kernel.org,
linux-kernel@vger.kernel.org, rafael@kernel.org,
peterz@infradead.org, adrian.hunter@intel.com,
sathyanarayanan.kuppuswamy@linux.intel.com,
elena.reshetova@intel.com, jun.nakajima@intel.com,
rick.p.edgecombe@intel.com, seanjc@google.com,
kai.huang@intel.com, bhe@redhat.com, kexec@lists.infradead.org,
linux-coco@lists.linux.dev, anisinha@redhat.com,
michael.roth@amd.com, bdas@redhat.com, vkuznets@redhat.com,
dionnaglaze@google.com, jroedel@suse.de,
ashwin.kamat@broadcom.com
Subject: Re: [PATCH 2/2] x86/snp: Convert shared memory back to private on kexec
Date: Thu, 22 Feb 2024 07:58:21 -0600 [thread overview]
Message-ID: <3b7a719b-d7ff-495e-af3f-a419e4b46d96@amd.com> (raw)
In-Reply-To: <amk4ozai3l65d6ef3k2rsnapaislbvlwpfx7p35tqqhesmc4w7@5vmi52a3qv3o>
On 2/22/24 04:50, Kirill A. Shutemov wrote:
> On Wed, Feb 21, 2024 at 02:35:13PM -0600, Tom Lendacky wrote:
>>> @@ -906,6 +917,206 @@ void snp_accept_memory(phys_addr_t start, phys_addr_t end)
>>> set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE);
>>> }
>>> +static inline bool pte_decrypted(pte_t pte)
>>> +{
>>> + return cc_mkdec(pte_val(pte)) == pte_val(pte);
>>> +}
>>> +
>>
>> This is duplicated in TDX code, arch/x86/coco/tdx/tdx.c, looks like
>> something that can go in a header file, maybe mem_encrypt.h.
>>
>
> I think <asm/pgtable.h> is a better fit.
>
>>> +void snp_kexec_stop_conversion(bool crash)
>>> +{
>>> + /* Stop new private<->shared conversions */
>>> + conversion_allowed = false;
>>> + crash_requested = crash;
>>> +
>>> + /*
>>> + * Make sure conversion_allowed is cleared before checking
>>> + * conversions_in_progress.
>>> + */
>>> + barrier();
>>
>> This should be smp_wmb().
>>
>
> Why?
IIUC, this is because conversions_in_progress can be set on another thread
and so this needs an smp barrier. In this case, smp_wmb() just ends up
being barrier(), but to me it is clearer this way. Just my opinion, though.
Thanks,
Tom
>
prev parent reply other threads:[~2024-02-22 13:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240212104448.2589568-1-kirill.shutemov@linux.intel.com>
2024-02-20 1:18 ` [PATCH 0/2] x86/snp: Add kexec support Ashish Kalra
2024-02-20 1:18 ` [PATCH 1/2] x86/mm: Do not zap PMD entry mapping unaccepted memory table during kdump Ashish Kalra
2024-02-20 12:42 ` Kirill A. Shutemov
2024-02-20 19:09 ` Kalra, Ashish
2024-02-20 1:18 ` [PATCH 2/2] x86/snp: Convert shared memory back to private on kexec Ashish Kalra
2024-02-21 20:35 ` Tom Lendacky
2024-02-22 10:50 ` Kirill A. Shutemov
2024-02-22 13:58 ` Tom Lendacky [this message]
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