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Re: [PATCH v10 1/2] vfio: move implement of vfio_get_xlat_addr() to memo
From: |
Michael S. Tsirkin |
Subject: |
Re: [PATCH v10 1/2] vfio: move implement of vfio_get_xlat_addr() to memory.c |
Date: |
Wed, 2 Nov 2022 08:45:00 -0400 |
On Mon, Oct 31, 2022 at 08:57:01PM +0800, Cindy Lu wrote:
> - Move the implement vfio_get_xlat_addr to softmmu/memory.c, and
> change the name to memory_get_xlat_addr(). So we can use this
> function on other devices, such as vDPA device.
> - Add a new function vfio_get_xlat_addr in vfio/common.c, and it will check
> whether the memory is backed by a discard manager. then device can
> have its own warning.
>
> Signed-off-by: Cindy Lu <lulu@redhat.com>
This is in my tree now, pls note this if you repost so
I don't get confused.
> ---
> hw/vfio/common.c | 66 +++------------------------------------
> include/exec/memory.h | 4 +++
> softmmu/memory.c | 72 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 81 insertions(+), 61 deletions(-)
>
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index ace9562a9b..6bc02b32c8 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -578,45 +578,11 @@ static bool
> vfio_listener_skipped_section(MemoryRegionSection *section)
> static bool vfio_get_xlat_addr(IOMMUTLBEntry *iotlb, void **vaddr,
> ram_addr_t *ram_addr, bool *read_only)
> {
> - MemoryRegion *mr;
> - hwaddr xlat;
> - hwaddr len = iotlb->addr_mask + 1;
> - bool writable = iotlb->perm & IOMMU_WO;
> -
> - /*
> - * The IOMMU TLB entry we have just covers translation through
> - * this IOMMU to its immediate target. We need to translate
> - * it the rest of the way through to memory.
> - */
> - mr = address_space_translate(&address_space_memory,
> - iotlb->translated_addr,
> - &xlat, &len, writable,
> - MEMTXATTRS_UNSPECIFIED);
> - if (!memory_region_is_ram(mr)) {
> - error_report("iommu map to non memory area %"HWADDR_PRIx"",
> - xlat);
> - return false;
> - } else if (memory_region_has_ram_discard_manager(mr)) {
> - RamDiscardManager *rdm = memory_region_get_ram_discard_manager(mr);
> - MemoryRegionSection tmp = {
> - .mr = mr,
> - .offset_within_region = xlat,
> - .size = int128_make64(len),
> - };
> -
> - /*
> - * Malicious VMs can map memory into the IOMMU, which is expected
> - * to remain discarded. vfio will pin all pages, populating memory.
> - * Disallow that. vmstate priorities make sure any RamDiscardManager
> - * were already restored before IOMMUs are restored.
> - */
> - if (!ram_discard_manager_is_populated(rdm, &tmp)) {
> - error_report("iommu map to discarded memory (e.g., unplugged via"
> - " virtio-mem): %"HWADDR_PRIx"",
> - iotlb->translated_addr);
> - return false;
> - }
> + bool ret, mr_has_discard_manager;
>
> + ret = memory_get_xlat_addr(iotlb, vaddr, ram_addr, read_only,
> + &mr_has_discard_manager);
> + if (ret && mr_has_discard_manager) {
> /*
> * Malicious VMs might trigger discarding of IOMMU-mapped memory. The
> * pages will remain pinned inside vfio until unmapped, resulting in
> a
> @@ -635,29 +601,7 @@ static bool vfio_get_xlat_addr(IOMMUTLBEntry *iotlb,
> void **vaddr,
> " intended via an IOMMU. It's possible to mitigate "
> " by setting/adjusting RLIMIT_MEMLOCK.");
> }
> -
> - /*
> - * Translation truncates length to the IOMMU page size,
> - * check that it did not truncate too much.
> - */
> - if (len & iotlb->addr_mask) {
> - error_report("iommu has granularity incompatible with target AS");
> - return false;
> - }
> -
> - if (vaddr) {
> - *vaddr = memory_region_get_ram_ptr(mr) + xlat;
> - }
> -
> - if (ram_addr) {
> - *ram_addr = memory_region_get_ram_addr(mr) + xlat;
> - }
> -
> - if (read_only) {
> - *read_only = !writable || mr->readonly;
> - }
> -
> - return true;
> + return ret;
> }
>
> static void vfio_iommu_map_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb)
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index bfb1de8eea..d1e79c39dc 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -713,6 +713,10 @@ void
> ram_discard_manager_register_listener(RamDiscardManager *rdm,
> void ram_discard_manager_unregister_listener(RamDiscardManager *rdm,
> RamDiscardListener *rdl);
>
> +bool memory_get_xlat_addr(IOMMUTLBEntry *iotlb, void **vaddr,
> + ram_addr_t *ram_addr, bool *read_only,
> + bool *mr_has_discard_manager);
> +
> typedef struct CoalescedMemoryRange CoalescedMemoryRange;
> typedef struct MemoryRegionIoeventfd MemoryRegionIoeventfd;
>
> diff --git a/softmmu/memory.c b/softmmu/memory.c
> index 7ba2048836..bc0be3f62c 100644
> --- a/softmmu/memory.c
> +++ b/softmmu/memory.c
> @@ -33,6 +33,7 @@
> #include "qemu/accel.h"
> #include "hw/boards.h"
> #include "migration/vmstate.h"
> +#include "exec/address-spaces.h"
>
> //#define DEBUG_UNASSIGNED
>
> @@ -2121,6 +2122,77 @@ void
> ram_discard_manager_unregister_listener(RamDiscardManager *rdm,
> rdmc->unregister_listener(rdm, rdl);
> }
>
> +/* Called with rcu_read_lock held. */
> +bool memory_get_xlat_addr(IOMMUTLBEntry *iotlb, void **vaddr,
> + ram_addr_t *ram_addr, bool *read_only,
> + bool *mr_has_discard_manager)
> +{
> + MemoryRegion *mr;
> + hwaddr xlat;
> + hwaddr len = iotlb->addr_mask + 1;
> + bool writable = iotlb->perm & IOMMU_WO;
> +
> + if (mr_has_discard_manager) {
> + *mr_has_discard_manager = false;
> + }
> + /*
> + * The IOMMU TLB entry we have just covers translation through
> + * this IOMMU to its immediate target. We need to translate
> + * it the rest of the way through to memory.
> + */
> + mr = address_space_translate(&address_space_memory,
> iotlb->translated_addr,
> + &xlat, &len, writable,
> MEMTXATTRS_UNSPECIFIED);
> + if (!memory_region_is_ram(mr)) {
> + error_report("iommu map to non memory area %" HWADDR_PRIx "", xlat);
> + return false;
> + } else if (memory_region_has_ram_discard_manager(mr)) {
> + RamDiscardManager *rdm = memory_region_get_ram_discard_manager(mr);
> + MemoryRegionSection tmp = {
> + .mr = mr,
> + .offset_within_region = xlat,
> + .size = int128_make64(len),
> + };
> + if (mr_has_discard_manager) {
> + *mr_has_discard_manager = true;
> + }
> + /*
> + * Malicious VMs can map memory into the IOMMU, which is expected
> + * to remain discarded. vfio will pin all pages, populating memory.
> + * Disallow that. vmstate priorities make sure any RamDiscardManager
> + * were already restored before IOMMUs are restored.
> + */
> + if (!ram_discard_manager_is_populated(rdm, &tmp)) {
> + error_report("iommu map to discarded memory (e.g., unplugged via"
> + " virtio-mem): %" HWADDR_PRIx "",
> + iotlb->translated_addr);
> + return false;
> + }
> + }
> +
> + /*
> + * Translation truncates length to the IOMMU page size,
> + * check that it did not truncate too much.
> + */
> + if (len & iotlb->addr_mask) {
> + error_report("iommu has granularity incompatible with target AS");
> + return false;
> + }
> +
> + if (vaddr) {
> + *vaddr = memory_region_get_ram_ptr(mr) + xlat;
> + }
> +
> + if (ram_addr) {
> + *ram_addr = memory_region_get_ram_addr(mr) + xlat;
> + }
> +
> + if (read_only) {
> + *read_only = !writable || mr->readonly;
> + }
> +
> + return true;
> +}
> +
> void memory_region_set_log(MemoryRegion *mr, bool log, unsigned client)
> {
> uint8_t mask = 1 << client;
> --
> 2.34.3
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