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From: Joerg Roedel <joro@8bytes.org>
To: Tianyu Lan <ltykernel@gmail.com>
Cc: kys@microsoft.com, haiyangz@microsoft.com,
	sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com,
	tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
	x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com,
	luto@kernel.org, peterz@infradead.org, konrad.wilk@oracle.com,
	boris.ostrovsky@oracle.com, jgross@suse.com,
	sstabellini@kernel.org, will@kernel.org, davem@davemloft.net,
	kuba@kernel.org, jejb@linux.ibm.com, martin.petersen@oracle.com,
	arnd@arndb.de, hch@lst.de, m.szyprowski@samsung.com,
	robin.murphy@arm.com, thomas.lendacky@amd.com,
	brijesh.singh@amd.com, ardb@kernel.org, Tianyu.Lan@microsoft.com,
	rientjes@google.com, martin.b.radev@gmail.com,
	akpm@linux-foundation.org, rppt@kernel.org,
	kirill.shutemov@linux.intel.com, aneesh.kumar@linux.ibm.com,
	krish.sadhukhan@oracle.com, saravanand@fb.com,
	xen-devel@lists.xenproject.org, pgonda@google.com,
	david@redhat.com, keescook@chromium.org, hannes@cmpxchg.org,
	sfr@canb.auug.org.au, michael.h.kelley@microsoft.com,
	iommu@lists.linux-foundation.org, linux-arch@vger.kernel.org,
	linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-scsi@vger.kernel.org, netdev@vger.kernel.org,
	vkuznets@redhat.com, anparri@microsoft.com
Subject: Re: [PATCH 07/13] HV/Vmbus: Add SNP support for VMbus channel initiate message
Date: Mon, 2 Aug 2021 14:58:26 +0200	[thread overview]
Message-ID: <YQfr8lsaghth8Zix@8bytes.org> (raw)
In-Reply-To: <20210728145232.285861-8-ltykernel@gmail.com>

On Wed, Jul 28, 2021 at 10:52:22AM -0400, Tianyu Lan wrote:
> +	if (hv_is_isolation_supported()) {
> +		vmbus_connection.monitor_pages_va[0]
> +			= vmbus_connection.monitor_pages[0];
> +		vmbus_connection.monitor_pages[0]
> +			= memremap(msg->monitor_page1, HV_HYP_PAGE_SIZE,
> +				   MEMREMAP_WB);
> +		if (!vmbus_connection.monitor_pages[0])
> +			return -ENOMEM;
> +
> +		vmbus_connection.monitor_pages_va[1]
> +			= vmbus_connection.monitor_pages[1];
> +		vmbus_connection.monitor_pages[1]
> +			= memremap(msg->monitor_page2, HV_HYP_PAGE_SIZE,
> +				   MEMREMAP_WB);
> +		if (!vmbus_connection.monitor_pages[1]) {
> +			memunmap(vmbus_connection.monitor_pages[0]);
> +			return -ENOMEM;
> +		}
> +
> +		memset(vmbus_connection.monitor_pages[0], 0x00,
> +		       HV_HYP_PAGE_SIZE);
> +		memset(vmbus_connection.monitor_pages[1], 0x00,
> +		       HV_HYP_PAGE_SIZE);
> +	}

Okay, let me see if I got this right. In Hyper-V Isolation VMs, when the
guest wants to make memory shared, it does":

	- Call to the Hypervisor the mark the pages shared. The
	  Hypervisor will do the RMP update and remap the pages at
	  (VTOM + pa)

	- The guest maps the memory again into its page-table, so that
	  the entries point to the correct GPA (which is above VTOM
	  now).

Or in other words, Hyper-V implements a hardware-independent and
configurable c-bit position, as the VTOM value is always power-of-two
aligned. Is that correct?
This would at least explain why there is no separate
allocation/dealloction of memory for the shared range.

Thanks,

	Joerg

  reply	other threads:[~2021-08-02 12:58 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-28 14:52 [PATCH 00/13] x86/Hyper-V: Add Hyper-V Isolation VM support Tianyu Lan
2021-07-28 14:52 ` [PATCH 01/13] x86/HV: Initialize GHCB page in Isolation VM Tianyu Lan
2021-08-02 11:53   ` Joerg Roedel
2021-08-02 12:35     ` Tianyu Lan
2021-07-28 14:52 ` [PATCH 02/13] x86/HV: Initialize shared memory boundary in the " Tianyu Lan
2021-07-28 14:52 ` [PATCH 03/13] x86/HV: Add new hvcall guest address host visibility support Tianyu Lan
2021-07-28 15:29   ` Dave Hansen
2021-07-29 12:49     ` Tianyu Lan
2021-08-02 12:01     ` Joerg Roedel
2021-08-02 12:59       ` Tianyu Lan
2021-08-02 13:11       ` Juergen Gross
2021-08-02 13:30         ` Joerg Roedel
2021-07-28 17:06   ` Dave Hansen
2021-07-29 13:01     ` Tianyu Lan
2021-07-29 14:09       ` Dave Hansen
2021-07-29 15:02         ` Tianyu Lan
2021-07-29 16:05           ` Dave Hansen
2021-07-30  2:52             ` Tianyu Lan
2021-07-28 14:52 ` [PATCH 04/13] HV: Mark vmbus ring buffer visible to host in Isolation VM Tianyu Lan
2021-08-02 12:07   ` Joerg Roedel
2021-08-02 12:56     ` Tianyu Lan
2021-08-02 12:59       ` Joerg Roedel
2021-08-02 13:08         ` Tianyu Lan
2021-07-28 14:52 ` [PATCH 05/13] HV: Add Write/Read MSR registers via ghcb page Tianyu Lan
2021-08-02 12:28   ` Joerg Roedel
2021-08-02 13:18     ` Tianyu Lan
2021-07-28 14:52 ` [PATCH 06/13] HV: Add ghcb hvcall support for SNP VM Tianyu Lan
2021-08-02 12:39   ` Joerg Roedel
2021-08-02 13:32     ` Tianyu Lan
2021-07-28 14:52 ` [PATCH 07/13] HV/Vmbus: Add SNP support for VMbus channel initiate message Tianyu Lan
2021-08-02 12:58   ` Joerg Roedel [this message]
2021-07-28 14:52 ` [PATCH 08/13] HV/Vmbus: Initialize VMbus ring buffer for Isolation VM Tianyu Lan
2021-07-28 14:52 ` [PATCH 09/13] DMA: Add dma_map_decrypted/dma_unmap_encrypted() function Tianyu Lan
2021-07-29 15:13   ` Tianyu Lan
2021-07-28 14:52 ` [PATCH 10/13] x86/Swiotlb: Add Swiotlb bounce buffer remap function for HV IVM Tianyu Lan
2021-07-29 16:29   ` Konrad Rzeszutek Wilk
2021-07-30  4:10     ` Tianyu Lan
2021-07-28 14:52 ` [PATCH 11/13] HV/IOMMU: Enable swiotlb bounce buffer for Isolation VM Tianyu Lan
2021-07-28 14:52 ` [PATCH 12/13] HV/Netvsc: Add Isolation VM support for netvsc driver Tianyu Lan
2021-07-28 14:52 ` [PATCH 13/13] HV/Storvsc: Add Isolation VM support for storvsc driver Tianyu Lan
2021-08-02 13:20   ` Joerg Roedel
2021-08-02 14:08     ` Tianyu Lan

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