From: Jason Gunthorpe <jgg@ziepe.ca>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>,
linux-coco@lists.linux.dev, kvmarm@lists.linux.dev,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, iommu@lists.linux.dev,
Andrew Morton <akpm@linux-foundation.org>,
christian.koenig@amd.com, Joerg Roedel <joro@8bytes.org>,
Marc Zyngier <maz@kernel.org>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Robin Murphy <robin.murphy@arm.com>,
Steven Price <steven.price@arm.com>,
Sumit Semwal <sumit.semwal@linaro.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Thomas Gleixner <tglx@kernel.org>, Will Deacon <will@kernel.org>,
dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
linux-media@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC PATCH v7 02/13] mm: Add an allocator for CoCo shared memory
Date: Wed, 23 Sep 2026 10:00:31 -0300 [thread overview]
Message-ID: <20260923130031.GE1540250@ziepe.ca> (raw)
In-Reply-To: <arOfD6syXOgQhZYA@arm.com>
On Wed, Sep 23, 2026 at 10:42:39AM +0100, Catalin Marinas wrote:
> On pKVM, we want set_memory_decrypted() to zero the buffer
> before the host can access it (I guess currently relying on __GFP_ZERO
> allocations). Since no cryptographic encryption takes place, there's not
> much point in memset'ing again after the operation as the content was
> already zeroed.
It sounds like this a pkvm unique thing, since RMM always makes the
memory hidden, pkvm flow should do it too. Either inside its guest
set_memory_decrypted() or inside the hypervisor like RMM.
Hypervisor doing it is the right place, hypervisor always needs to
ensure guest memory is cleansed whenever the guest gives it up. Either
via a private to shared, unmap or just exiting.
> I don't think cc_make_shared() has the right information on how to
> safely and efficiently do the zeroing. That's only known to the
> set_memory_* backend. So you'd have to propagate the flag down.
+1
Jason
next prev parent reply other threads:[~2026-09-23 13:00 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-21 14:48 [RFC PATCH v7 00/13] coco: guest: Add a shared-granule allocator for host-shared memory Aneesh Kumar K.V (Arm)
2026-09-21 14:48 ` [RFC PATCH v7 01/13] arm64: realm: Add RHI helper to query IPA state change alignment Aneesh Kumar K.V (Arm)
2026-09-21 14:48 ` [RFC PATCH v7 02/13] mm: Add an allocator for CoCo shared memory Aneesh Kumar K.V (Arm)
2026-09-22 16:25 ` Catalin Marinas
2026-09-22 16:51 ` Jason Gunthorpe
2026-09-23 0:33 ` Suzuki K Poulose
2026-09-23 5:53 ` Aneesh Kumar K.V
2026-09-23 8:31 ` Aneesh Kumar K.V
2026-09-23 10:10 ` Catalin Marinas
2026-09-23 9:42 ` Catalin Marinas
2026-09-23 9:59 ` Aneesh Kumar K.V
2026-09-23 10:28 ` Aneesh Kumar K.V
2026-09-23 10:40 ` Catalin Marinas
2026-09-23 13:06 ` Jason Gunthorpe
2026-09-23 14:58 ` Aneesh Kumar K.V
2026-09-23 15:11 ` Suzuki K Poulose
2026-09-23 15:21 ` Jason Gunthorpe
2026-09-23 13:00 ` Jason Gunthorpe [this message]
2026-09-23 15:20 ` Mostafa Saleh
2026-09-21 14:48 ` [RFC PATCH v7 03/13] arm64: realm: Expose the CCA shared granule size through mem_encrypt ops Aneesh Kumar K.V (Arm)
2026-09-21 14:48 ` [RFC PATCH v7 04/13] irqchip/gic-v3-its: Resolve the default NUMA node explicitly Aneesh Kumar K.V (Arm)
2026-09-21 14:48 ` [RFC PATCH v7 05/13] irqchip/gic-v3-its: Allocate shared tables using CoCo shared memory allocator Aneesh Kumar K.V (Arm)
2026-09-21 14:48 ` [RFC PATCH v7 06/13] dma-contiguous: Accept an explicit minimum alignment Aneesh Kumar K.V (Arm)
2026-09-23 10:35 ` Catalin Marinas
2026-09-23 11:49 ` Aneesh Kumar K.V
2026-09-23 13:49 ` Catalin Marinas
2026-09-21 14:48 ` [RFC PATCH v7 07/13] dma-pool: Allocate CoCo atomic pools using CoCo shared memory allocator Aneesh Kumar K.V (Arm)
2026-09-21 14:48 ` [RFC PATCH v7 08/13] dma-direct: Align CoCo shared DMA allocations to the shared granule size Aneesh Kumar K.V (Arm)
2026-09-21 14:48 ` [RFC PATCH v7 09/13] swiotlb: Align shared IO TLB pools " Aneesh Kumar K.V (Arm)
2026-09-21 14:48 ` [RFC PATCH v7 10/13] swiotlb: Reject misaligned restricted DMA pools for CoCo guests Aneesh Kumar K.V (Arm)
2026-09-21 14:48 ` [RFC PATCH v7 11/13] dma-buf: system_heap: Limit scatterlist entries to the buffer size Aneesh Kumar K.V (Arm)
2026-09-21 14:48 ` [RFC PATCH v7 12/13] dma-buf: system_heap: Allocate shared buffers using CoCo shared memory allocator Aneesh Kumar K.V (Arm)
2026-09-22 16:39 ` Catalin Marinas
2026-09-23 8:32 ` Aneesh Kumar K.V
2026-09-23 8:46 ` Christian König
2026-09-21 14:48 ` [RFC PATCH v7 13/13] swiotlb: Make rounded shared pool capacity allocatable Aneesh Kumar K.V (Arm)
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