From: Juergen Gross <jgross@suse.com>
To: Christoph Hellwig <hch@lst.de>
Cc: "Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>,
"Stefano Stabellini" <sstabellini@kernel.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
"Ben Skeggs" <bskeggs@redhat.com>,
"Karol Herbst" <kherbst@redhat.com>,
"Lyude Paul" <lyude@redhat.com>,
xen-devel@lists.xenproject.org, iommu@lists.linux.dev,
linux-kernel@vger.kernel.org, nouveau@lists.freedesktop.org
Subject: Re: [PATCH 2/4] x86: always initialize xen-swiotlb when xen-pcifront is enabling
Date: Mon, 12 Jun 2023 10:08:07 +0200 [thread overview]
Message-ID: <afc27bd9-5426-d837-dbb2-ec9083bec240@suse.com> (raw)
In-Reply-To: <79b26dac-b507-1c05-b499-784ca6ee3db0@suse.com>
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On 09.06.23 17:38, Juergen Gross wrote:
> On 07.06.23 15:12, Christoph Hellwig wrote:
>> On Mon, May 22, 2023 at 10:37:09AM +0200, Juergen Gross wrote:
>>> In normal cases PCI passthrough in PV guests requires to start the guest
>>> with e820_host=1. So it should be rather easy to limit allocating the
>>> 64MB in PV guests to the cases where the memory map has non-RAM regions
>>> especially in the first 1MB of the memory.
>>>
>>> This will cover even hotplug cases. The only case not covered would be a
>>> guest started with e820_host=1 even if no PCI passthrough was planned.
>>> But this should be rather rare (at least I hope so).
>>
>> So is this an ACK for the patch and can we go ahead with it?
>
> As long as above mentioned check of the E820 map is done, yes.
>
> If you want I can send a diff to be folded into your patch on Monday.
Attached is a patch for adding a new flag xen_pv_pci_possible. You can
either add the patch to your series or merge it into your patch 2.
You need to modify your patch like this:
@@ -111,7 +90,10 @@ static inline void __init pci_xen_swiotlb_init(void)
void __init pci_iommu_alloc(void)
{
if (xen_pv_domain()) {
- if (xen_initial_domain() || x86_swiotlb_enable)
+ if (xen_initial_domain() ||
+ (IS_ENABLED(CONFIG_XEN_PCIDEV_FRONTEND) &&
+ xen_pv_pci_possible) ||
+ x86_swiotlb_enable)
pci_xen_swiotlb_init();
return;
}
Juergen
[-- Attachment #1.1.2: 0001-xen-pci-add-flag-for-PCI-passthrough-being-possible.patch --]
[-- Type: text/x-patch, Size: 1903 bytes --]
From 7e84a88243b57bc90d1ef6bd42661f499886e659 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@suse.com>
Date: Mon, 12 Jun 2023 09:57:18 +0200
Subject: [PATCH] xen/pci: add flag for PCI passthrough being possible
When running as a Xen PV guests passed through PCI devices only have a
chance to work if the Xen supplied memory map has some PCI space
reserved.
Add a flag xen_pv_pci_possible which will be set in early boot in case
the memory map has at least one area with the type E820_TYPE_RESERVED.
Signed-off-by: Juergen Gross <jgross@suse.com>
---
arch/x86/xen/setup.c | 6 ++++++
include/xen/xen.h | 6 ++++++
2 files changed, 12 insertions(+)
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index c2be3efb2ba0..716f76c41416 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -43,6 +43,9 @@ struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;
/* Number of pages released from the initial allocation. */
unsigned long xen_released_pages;
+/* Memory map would allow PCI passthrough. */
+bool xen_pv_pci_possible;
+
/* E820 map used during setting up memory. */
static struct e820_table xen_e820_table __initdata;
@@ -804,6 +807,9 @@ char * __init xen_memory_setup(void)
chunk_size = size;
type = xen_e820_table.entries[i].type;
+ if (type == E820_TYPE_RESERVED)
+ xen_pv_pci_possible = true;
+
if (type == E820_TYPE_RAM) {
if (addr < mem_end) {
chunk_size = min(size, mem_end - addr);
diff --git a/include/xen/xen.h b/include/xen/xen.h
index 0efeb652f9b8..5eb0a974a11e 100644
--- a/include/xen/xen.h
+++ b/include/xen/xen.h
@@ -29,6 +29,12 @@ extern bool xen_pvh;
extern uint32_t xen_start_flags;
+#ifdef CONFIG_XEN_PV
+extern bool xen_pv_pci_possible;
+#else
+#define xen_pv_pci_possible 0
+#endif
+
#include <xen/interface/hvm/start_info.h>
extern struct hvm_start_info pvh_start_info;
--
2.35.3
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next prev parent reply other threads:[~2023-06-12 8:08 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-18 13:42 unexport swiotlb_active Christoph Hellwig
2023-05-18 13:42 ` [PATCH 1/4] x86: move a check out of pci_xen_swiotlb_init Christoph Hellwig
2023-05-18 13:42 ` [PATCH 2/4] x86: always initialize xen-swiotlb when xen-pcifront is enabling Christoph Hellwig
2023-05-18 18:18 ` Marek Marczykowski-Górecki
2023-05-19 4:04 ` Christoph Hellwig
2023-05-19 10:10 ` Marek Marczykowski-Górecki
2023-05-19 12:41 ` Christoph Hellwig
2023-05-19 12:49 ` Andrew Cooper
2023-05-19 12:58 ` Christoph Hellwig
2023-05-20 6:21 ` Christoph Hellwig
2023-05-22 7:52 ` Petr Tesařík
2023-05-22 7:54 ` Petr Tesařík
2023-05-22 8:37 ` Juergen Gross
2023-06-07 13:12 ` Christoph Hellwig
2023-06-09 15:38 ` Juergen Gross
2023-06-12 6:47 ` Christoph Hellwig
2023-06-12 8:08 ` Juergen Gross [this message]
2023-06-12 8:23 ` Christoph Hellwig
2023-05-18 13:42 ` [PATCH 3/4] drm/nouveau: stop using is_swiotlb_active Christoph Hellwig
2023-05-18 20:30 ` Lyude Paul
2023-06-07 13:11 ` Christoph Hellwig
2023-05-18 13:42 ` [PATCH 4/4] swiotlb: unexport is_swiotlb_active Christoph Hellwig
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