From: "Pratik R. Sampat" <prsampat@amd.com>
To: Kiryl Shutsemau <kas@kernel.org>, Dave Hansen <dave.hansen@intel.com>
Cc: linux-mm@kvack.org, linux-coco@lists.linux.dev, x86@kernel.org,
linux-kernel@vger.kernel.org, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
ardb@kernel.org, akpm@linux-foundation.org, david@kernel.org,
osalvador@suse.de, thomas.lendacky@amd.com, michael.roth@amd.com
Subject: Re: [PATCH v3 2/2] x86/sev: Add support to unaccept memory after hot-remove
Date: Thu, 29 Jan 2026 11:32:37 -0600 [thread overview]
Message-ID: <097a4980-9d10-40d2-9667-d07bf19e7b86@amd.com> (raw)
In-Reply-To: <aXs4DTXCbI_c0JPO@thinkstation>
On 1/29/26 4:40 AM, Kiryl Shutsemau wrote:
> On Wed, Jan 28, 2026 at 01:15:06PM -0800, Dave Hansen wrote:
>> On 1/28/26 12:41, Pratik R. Sampat wrote:
>>> +static inline void arch_unaccept_memory(phys_addr_t start, phys_addr_t end)
>>> +{
>>> + if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) {
>>> + snp_unaccept_memory(start, end);
>>> + } else {
>>> + panic("Cannot unaccept memory: unknown platform\n");
>>> + }
>>> +}
>>
>> This panic() is pretty nasty.
>>
>> Can't we just disable memory hotplug up front if it's:
>>
>> !cc_platform_has(CC_ATTR_GUEST_SEV_SNP)
>>
>> ?
>
> I don't understand SEV-SNP situation, but I don't think we need to do
> anything on unplug for TDX. We should expect the unplugged memory to be
> removed from SEPT. If VMM doesn't do this, it is effectively DoS and we
> don't protect against DoS in CoCo.
>
> Converting the memory to shared will do no good for us.
In that case a fall through for TDX (with a comment explaining why) and
panic for rest may be the way to go?
>
next prev parent reply other threads:[~2026-01-29 17:33 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-28 20:41 [PATCH v3 0/2] SEV-SNP Unaccepted Memory Hotplug Pratik R. Sampat
2026-01-28 20:41 ` [PATCH v3 1/2] mm/memory_hotplug: Add support to accept memory during hot-add Pratik R. Sampat
2026-01-29 10:35 ` Kiryl Shutsemau
2026-01-29 17:32 ` Pratik R. Sampat
2026-01-28 20:41 ` [PATCH v3 2/2] x86/sev: Add support to unaccept memory after hot-remove Pratik R. Sampat
2026-01-28 21:08 ` Andrew Morton
2026-01-28 22:25 ` Pratik R. Sampat
2026-01-28 21:15 ` Dave Hansen
2026-01-29 10:40 ` Kiryl Shutsemau
2026-01-29 17:32 ` Pratik R. Sampat [this message]
2026-01-29 17:39 ` Dave Hansen
2026-01-29 19:32 ` Pratik R. Sampat
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