qemu-devel
[Top][All Lists]
Advanced
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [RFC PATCH qemu v2 1/5] vfio: Switch from TARGET_PAGE_M

From: Alexey Kardashevskiy
Subject: Re: [Qemu-devel] [RFC PATCH qemu v2 1/5] vfio: Switch from TARGET_PAGE_MASK to qemu_real_host_page_mask
Date: Tue, 14 Jul 2015 16:58:14 +1000
User-agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.0.1 
On 07/14/2015 05:13 AM, Alex Williamson wrote:

On Tue, 2015-07-14 at 00:56 +1000, Alexey Kardashevskiy wrote:

These started switching from TARGET_PAGE_MASK (hardcoded as 4K) to
a real host page size:
4e51361d7 "cpu-all: complete "real" host page size API" and
f7ceed190 "vfio: cpu: Use "real" page size API"

This finished the transition by:
- %s/TARGET_PAGE_MASK/qemu_real_host_page_mask/
- %s/TARGET_PAGE_ALIGN/REAL_HOST_PAGE_ALIGN/
- removing bitfield length for offsets in VFIOQuirk::data as
qemu_real_host_page_mask is not a macro


Can we assume that none of the changes to quirks have actually been
tested?


No, why? :) I tried it on one of NVIDIAs I got here -
VGA compatible controller: NVIDIA Corporation GM107GL [Quadro K2200] (rev a2)
The driver was from NVIDIA (not nouveau) and the test was "acos" (some basic CUDA test). 


I don't really support them being bundled in here since they
really aren't related to what you're doing.
This makes sense, I'll move them to a separate patch and add a note how it helps on a 64k-pages host. 


For DMA we generally want
to be host IOMMU page aligned,
Do all known IOMMUs use a constant page size? IOMMU memory region does not have an IOMMU page size/mask and I wanted to add it there but not sure if it is generic enough. 


which we can generally assume is the same
as host page aligned,


They are almost never the same on sPAPR for 32bit windows...


but quirks are simply I/O regions, so I think they
ought to continue to be target page aligned.
Without s/TARGET_PAGE_MASK/qemu_real_host_page_mask/, &vfio_nvidia_88000_quirk fails+exits in kvm_set_phys_mem() as the size of section is 0x88000. It still works with x-mmap=false (or TCG, I suppose) though. 



This keeps using TARGET_PAGE_MASK for IOMMU regions though as it is
the minimum page size which IOMMU regions may be using and at the moment
memory regions do not carry the actual page size.

Signed-off-by: Alexey Kardashevskiy <address@hidden>
---

In reality DMA windows are always a lot bigger than a single 4K page
and aligned to 32/64MB, may be only use here qemu_real_host_page_mask?


I don't understand what this is asking either.  While the bulk of memory
is going to be mapped in larger chunks, we do occasionally see 4k
mappings on x86, particularly in some of the legacy low memory areas.
The question was not about individual mappings - these are handled by a iommu memory region notifier; here we are dealing with DMA windows which are always megabytes but nothing really prevents/prohibits a guest from requesting a 4K _window_ (with a single TCE entry). Whether we want to support such small windows or not - this was a question. 





---
  hw/vfio/common.c | 26 ++++++++++++++++----------
  hw/vfio/pci.c    | 30 +++++++++++++++---------------
  2 files changed, 31 insertions(+), 25 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 85ee9b0..d115ec9 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -321,6 +321,9 @@ static void vfio_listener_region_add(MemoryListener 
*listener,
      Int128 llend;
      void *vaddr;
      int ret;
+    const bool is_iommu = memory_region_is_iommu(section->mr);
+    const hwaddr page_mask =
+        is_iommu ? TARGET_PAGE_MASK : qemu_real_host_page_mask;

      if (vfio_listener_skipped_section(section)) {
          trace_vfio_listener_region_add_skip(
@@ -330,16 +333,16 @@ static void vfio_listener_region_add(MemoryListener 
*listener,
          return;
      }

-    if (unlikely((section->offset_within_address_space & ~TARGET_PAGE_MASK) !=
-                 (section->offset_within_region & ~TARGET_PAGE_MASK))) {
+    if (unlikely((section->offset_within_address_space & ~page_mask) !=
+                 (section->offset_within_region & ~page_mask))) {
          error_report("%s received unaligned region", __func__);
          return;
      }

-    iova = TARGET_PAGE_ALIGN(section->offset_within_address_space);
+    iova = ROUND_UP(section->offset_within_address_space, ~page_mask + 1);
      llend = int128_make64(section->offset_within_address_space);
      llend = int128_add(llend, section->size);
-    llend = int128_and(llend, int128_exts64(TARGET_PAGE_MASK));
+    llend = int128_and(llend, int128_exts64(page_mask));

      if (int128_ge(int128_make64(iova), llend)) {
          return;
@@ -347,7 +350,7 @@ static void vfio_listener_region_add(MemoryListener 
*listener,

      memory_region_ref(section->mr);

-    if (memory_region_is_iommu(section->mr)) {
+    if (is_iommu) {
          VFIOGuestIOMMU *giommu;

          trace_vfio_listener_region_add_iommu(iova,
@@ -423,6 +426,9 @@ static void vfio_listener_region_del(MemoryListener 
*listener,
                                              iommu_data.type1.listener);
      hwaddr iova, end;
      int ret;
+    const bool is_iommu = memory_region_is_iommu(section->mr);
+    const hwaddr page_mask =
+        is_iommu ? TARGET_PAGE_MASK : qemu_real_host_page_mask;

      if (vfio_listener_skipped_section(section)) {
          trace_vfio_listener_region_del_skip(
@@ -432,13 +438,13 @@ static void vfio_listener_region_del(MemoryListener 
*listener,
          return;
      }

-    if (unlikely((section->offset_within_address_space & ~TARGET_PAGE_MASK) !=
-                 (section->offset_within_region & ~TARGET_PAGE_MASK))) {
+    if (unlikely((section->offset_within_address_space & ~page_mask) !=
+                 (section->offset_within_region & ~page_mask))) {
          error_report("%s received unaligned region", __func__);
          return;
      }

-    if (memory_region_is_iommu(section->mr)) {
+    if (is_iommu) {
          VFIOGuestIOMMU *giommu;

          QLIST_FOREACH(giommu, &container->giommu_list, giommu_next) {
@@ -459,9 +465,9 @@ static void vfio_listener_region_del(MemoryListener 
*listener,
           */
      }

-    iova = TARGET_PAGE_ALIGN(section->offset_within_address_space);
+    iova = REAL_HOST_PAGE_ALIGN(section->offset_within_address_space);
      end = (section->offset_within_address_space + int128_get64(section->size)) 
&
-          TARGET_PAGE_MASK;
+          page_mask;

      if (iova >= end) {
          return;
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 2ed877f..7694afe 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -50,16 +50,16 @@ typedef struct VFIOQuirk {
      struct VFIOPCIDevice *vdev;
      QLIST_ENTRY(VFIOQuirk) next;
      struct {
-        uint32_t base_offset:TARGET_PAGE_BITS;
-        uint32_t address_offset:TARGET_PAGE_BITS;
+        uint32_t base_offset;
+        uint32_t address_offset;
          uint32_t address_size:3;
          uint32_t bar:3;

          uint32_t address_match;
          uint32_t address_mask;

-        uint32_t address_val:TARGET_PAGE_BITS;
-        uint32_t data_offset:TARGET_PAGE_BITS;
+        uint32_t address_val;
+        uint32_t data_offset;
          uint32_t data_size:3;

          uint8_t flags;
@@ -1319,8 +1319,8 @@ static uint64_t vfio_generic_quirk_read(void *opaque,
  {
      VFIOQuirk *quirk = opaque;
      VFIOPCIDevice *vdev = quirk->vdev;
-    hwaddr base = quirk->data.address_match & TARGET_PAGE_MASK;
-    hwaddr offset = quirk->data.address_match & ~TARGET_PAGE_MASK;
+    hwaddr base = quirk->data.address_match & qemu_real_host_page_mask;
+    hwaddr offset = quirk->data.address_match & ~qemu_real_host_page_mask;
      uint64_t data;

      if (vfio_flags_enabled(quirk->data.flags, quirk->data.read_flags) &&
@@ -1349,8 +1349,8 @@ static void vfio_generic_quirk_write(void *opaque, hwaddr 
addr,
  {
      VFIOQuirk *quirk = opaque;
      VFIOPCIDevice *vdev = quirk->vdev;
-    hwaddr base = quirk->data.address_match & TARGET_PAGE_MASK;
-    hwaddr offset = quirk->data.address_match & ~TARGET_PAGE_MASK;
+    hwaddr base = quirk->data.address_match & qemu_real_host_page_mask;
+    hwaddr offset = quirk->data.address_match & ~qemu_real_host_page_mask;

      if (vfio_flags_enabled(quirk->data.flags, quirk->data.write_flags) &&
          ranges_overlap(addr, size, offset, quirk->data.address_mask + 1)) {
@@ -1650,9 +1650,9 @@ static void vfio_probe_ati_bar2_4000_quirk(VFIOPCIDevice 
*vdev, int nr)

      memory_region_init_io(&quirk->mem, OBJECT(vdev), &vfio_generic_quirk, 
quirk,
                            "vfio-ati-bar2-4000-quirk",
-                          TARGET_PAGE_ALIGN(quirk->data.address_mask + 1));
+                          REAL_HOST_PAGE_ALIGN(quirk->data.address_mask + 1));
      memory_region_add_subregion_overlap(&vdev->bars[nr].region.mem,
-                          quirk->data.address_match & TARGET_PAGE_MASK,
+                          quirk->data.address_match & qemu_real_host_page_mask,
                            &quirk->mem, 1);

      QLIST_INSERT_HEAD(&vdev->bars[nr].quirks, quirk, next);
@@ -1888,7 +1888,7 @@ static void vfio_nvidia_88000_quirk_write(void *opaque, 
hwaddr addr,
      VFIOQuirk *quirk = opaque;
      VFIOPCIDevice *vdev = quirk->vdev;
      PCIDevice *pdev = &vdev->pdev;
-    hwaddr base = quirk->data.address_match & TARGET_PAGE_MASK;
+    hwaddr base = quirk->data.address_match & qemu_real_host_page_mask;

      vfio_generic_quirk_write(opaque, addr, data, size);

@@ -1943,9 +1943,9 @@ static void 
vfio_probe_nvidia_bar0_88000_quirk(VFIOPCIDevice *vdev, int nr)

      memory_region_init_io(&quirk->mem, OBJECT(vdev), &vfio_nvidia_88000_quirk,
                            quirk, "vfio-nvidia-bar0-88000-quirk",
-                          TARGET_PAGE_ALIGN(quirk->data.address_mask + 1));
+                          REAL_HOST_PAGE_ALIGN(quirk->data.address_mask + 1));
      memory_region_add_subregion_overlap(&vdev->bars[nr].region.mem,
-                          quirk->data.address_match & TARGET_PAGE_MASK,
+                          quirk->data.address_match & qemu_real_host_page_mask,
                            &quirk->mem, 1);

      QLIST_INSERT_HEAD(&vdev->bars[nr].quirks, quirk, next);
@@ -1980,9 +1980,9 @@ static void 
vfio_probe_nvidia_bar0_1800_quirk(VFIOPCIDevice *vdev, int nr)

      memory_region_init_io(&quirk->mem, OBJECT(vdev), &vfio_generic_quirk, 
quirk,
                            "vfio-nvidia-bar0-1800-quirk",
-                          TARGET_PAGE_ALIGN(quirk->data.address_mask + 1));
+                          REAL_HOST_PAGE_ALIGN(quirk->data.address_mask + 1));
      memory_region_add_subregion_overlap(&vdev->bars[nr].region.mem,
-                          quirk->data.address_match & TARGET_PAGE_MASK,
+                          quirk->data.address_match & qemu_real_host_page_mask,
                            &quirk->mem, 1);

      QLIST_INSERT_HEAD(&vdev->bars[nr].quirks, quirk, next);







--
Alexey
reply via email to
[Prev in Thread] Current Thread [Next in Thread]