Re: [Qemu-devel] [PATCH 3/4] memory: split memory_region_from_host from qemu_ram_addr_from_host

[Marc-André Lureau]

Hi

On Thu, May 26, 2016 at 10:49 AM, Paolo Bonzini <address@hidden> wrote:
> Move the old qemu_ram_addr_from_host to memory_region_from_host and
> make it return an offset within the region.  For qemu_ram_addr_from_host
> return the ram_addr_t directly, similar to what it was before
> commit 1b5ec23 ("memory: return MemoryRegion from qemu_ram_addr_from_host",
> 2013-07-04).
>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
>  cputlb.c                  |  3 ++-
>  exec.c                    | 10 +++++-----
>  hw/virtio/vhost-user.c    | 16 +++++++---------
>  include/exec/cpu-common.h |  2 +-
>  include/exec/memory.h     | 20 ++++++++++++++++++++
>  memory.c                  | 14 ++++++++++++--
>  target-i386/kvm.c         |  6 ++++--
>  7 files changed, 51 insertions(+), 20 deletions(-)
>
> diff --git a/cputlb.c b/cputlb.c
> index 1ff6354..23c9b91 100644
> --- a/cputlb.c
> +++ b/cputlb.c
> @@ -246,7 +246,8 @@ static inline ram_addr_t 
> qemu_ram_addr_from_host_nofail(void *ptr)
>  {
>      ram_addr_t ram_addr;
>
> -    if (qemu_ram_addr_from_host(ptr, &ram_addr) == NULL) {
> +    ram_addr = qemu_ram_addr_from_host(ptr);
> +    if (ram_addr == RAM_ADDR_INVALID) {
>          fprintf(stderr, "Bad ram pointer %p\n", ptr);
>          abort();
>      }
> diff --git a/exec.c b/exec.c
> index 65bad53..7f62835 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1964,18 +1964,17 @@ RAMBlock *qemu_ram_block_by_name(const char *name)
>
>  /* Some of the softmmu routines need to translate from a host pointer
>     (typically a TLB entry) back to a ram offset.  */
> -MemoryRegion *qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr)
> +ram_addr_t qemu_ram_addr_from_host(void *ptr)
>  {
>      RAMBlock *block;
>      ram_addr_t offset;
>
>      block = qemu_ram_block_from_host(ptr, false, &offset);
> -    *ram_addr = block->offset + offset;
>      if (!block) {
> -        return NULL;
> +        return RAM_ADDR_INVALID;
>      }
>
> -    return block->mr;
> +    return block->offset + offset;
>  }
>
>  /* Called within RCU critical section.  */
> @@ -2975,8 +2974,9 @@ void address_space_unmap(AddressSpace *as, void 
> *buffer, hwaddr len,
>          MemoryRegion *mr;
>          ram_addr_t addr1;
>
> -        mr = qemu_ram_addr_from_host(buffer, &addr1);
> +        mr = memory_region_from_host(buffer, &addr1);
>          assert(mr != NULL);
> +        addr1 += memory_region_get_ram_addr(mr);
>          if (is_write) {
>              invalidate_and_set_dirty(mr, addr1, access_len);
>          }
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 41908c0..495e09f 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -17,7 +17,6 @@
>  #include "sysemu/kvm.h"
>  #include "qemu/error-report.h"
>  #include "qemu/sockets.h"
> -#include "exec/ram_addr.h"
>  #include "migration/migration.h"
>
>  #include <sys/ioctl.h>
> @@ -247,19 +246,18 @@ static int vhost_user_set_mem_table(struct vhost_dev 
> *dev,
>
>      for (i = 0; i < dev->mem->nregions; ++i) {
>          struct vhost_memory_region *reg = dev->mem->regions + i;
> -        ram_addr_t ram_addr;
> +        ram_addr_t offset;
>          MemoryRegion *mr;
>
>          assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
> -        mr = qemu_ram_addr_from_host((void *)(uintptr_t)reg->userspace_addr,
> -                                     &ram_addr);
> +        mr = memory_region_from_host((void *)(uintptr_t)reg->userspace_addr,
> +                                     &offset);
>          fd = memory_region_get_fd(mr);
>          if (fd > 0) {
>              msg.payload.memory.regions[fd_num].userspace_addr = 
> reg->userspace_addr;
>              msg.payload.memory.regions[fd_num].memory_size  = 
> reg->memory_size;
>              msg.payload.memory.regions[fd_num].guest_phys_addr = 
> reg->guest_phys_addr;
> -            msg.payload.memory.regions[fd_num].mmap_offset = 
> reg->userspace_addr -
> -                (uintptr_t) memory_region_get_ram_ptr(mr);
> +            msg.payload.memory.regions[fd_num].mmap_offset = offset;
>              assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
>              fds[fd_num++] = fd;
>          }
> @@ -617,14 +615,14 @@ static bool vhost_user_can_merge(struct vhost_dev *dev,
>                                   uint64_t start1, uint64_t size1,
>                                   uint64_t start2, uint64_t size2)
>  {
> -    ram_addr_t ram_addr;
> +    ram_addr_t offset;
>      int mfd, rfd;
>      MemoryRegion *mr;
>
> -    mr = qemu_ram_addr_from_host((void *)(uintptr_t)start1, &ram_addr);
> +    mr = memory_region_from_host((void *)(uintptr_t)start1, &offset);
>      mfd = memory_region_get_fd(mr);
>
> -    mr = qemu_ram_addr_from_host((void *)(uintptr_t)start2, &ram_addr);
> +    mr = memory_region_from_host((void *)(uintptr_t)start2, &offset);
>      rfd = memory_region_get_fd(mr);
>
>      return mfd == rfd;
> diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
> index fc609ad..aaee995 100644
> --- a/include/exec/cpu-common.h
> +++ b/include/exec/cpu-common.h
> @@ -57,7 +57,7 @@ typedef uint32_t CPUReadMemoryFunc(void *opaque, hwaddr 
> addr);
>
>  void qemu_ram_remap(ram_addr_t addr, ram_addr_t length);
>  /* This should not be used by devices.  */
> -MemoryRegion *qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr);
> +ram_addr_t qemu_ram_addr_from_host(void *ptr);
>  RAMBlock *qemu_ram_block_by_name(const char *name);
>  RAMBlock *qemu_ram_block_from_host(void *ptr, bool round_offset,
>                                     ram_addr_t *offset);
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 1678494..71a27ab 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -32,6 +32,8 @@
>  #include "qom/object.h"
>  #include "qemu/rcu.h"
>
> +#define RAM_ADDR_INVALID (~(ram_addr_t)0)
> +
>  #define MAX_PHYS_ADDR_SPACE_BITS 62
>  #define MAX_PHYS_ADDR            (((hwaddr)1 << MAX_PHYS_ADDR_SPACE_BITS) - 
> 1)
>
> @@ -678,6 +680,24 @@ int memory_region_get_fd(MemoryRegion *mr);
>  void memory_region_set_fd(MemoryRegion *mr, int fd);
>
>  /**
> + * memory_region_from_host: Convert a pointer into a RAM memory region
> + * and an offset within it.
> + *
> + * Given a host pointer inside a RAM memory region (created with
> + * memory_region_init_ram() or memory_region_init_ram_ptr()), return
> + * the MemoryRegion and the offset within it.
> + *
> + * Use with care; by the time this function returns, the returned pointer is
> + * not protected by RCU anymore.  If the caller is not within an RCU critical
> + * section and does not hold the iothread lock, it must have other means of
> + * protecting the pointer, such as a reference to the region that includes
> + * the incoming ram_addr_t.
> + *
> + * @mr: the memory region being queried.

@ptr: host pointer to look up
@offset: set to result offset within the MemoryRegion

> + */
> +MemoryRegion *memory_region_from_host(void *ptr, ram_addr_t *offset);
> +
> +/**
>   * memory_region_get_ram_ptr: Get a pointer into a RAM memory region.
>   *
>   * Returns a host pointer to a RAM memory region (created with
> diff --git a/memory.c b/memory.c
> index d6a4a68..f8085ea 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -33,8 +33,6 @@
>
>  //#define DEBUG_UNASSIGNED
>
> -#define RAM_ADDR_INVALID (~(ram_addr_t)0)
> -
>  static unsigned memory_region_transaction_depth;
>  static bool memory_region_update_pending;
>  static bool ioeventfd_update_pending;
> @@ -1665,6 +1663,18 @@ void *memory_region_get_ram_ptr(MemoryRegion *mr)
>      return ptr + offset;
>  }
>
> +MemoryRegion *memory_region_from_host(void *ptr, ram_addr_t *offset)
> +{
> +    RAMBlock *block;
> +
> +    block = qemu_ram_block_from_host(ptr, false, offset);
> +    if (!block) {
> +        return NULL;
> +    }
> +
> +    return block->mr;
> +}
> +
>  ram_addr_t memory_region_get_ram_addr(MemoryRegion *mr)
>  {
>      return mr->ram_block ? mr->ram_block->offset : RAM_ADDR_INVALID;
> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> index 7b3667a..abf50e6 100644
> --- a/target-i386/kvm.c
> +++ b/target-i386/kvm.c
> @@ -411,7 +411,8 @@ int kvm_arch_on_sigbus_vcpu(CPUState *c, int code, void 
> *addr)
>
>      if ((env->mcg_cap & MCG_SER_P) && addr
>          && (code == BUS_MCEERR_AR || code == BUS_MCEERR_AO)) {
> -        if (qemu_ram_addr_from_host(addr, &ram_addr) == NULL ||
> +        ram_addr = qemu_ram_addr_from_host(addr);
> +        if (ram_addr == RAM_ADDR_INVALID ||
>              !kvm_physical_memory_addr_from_host(c->kvm_state, addr, &paddr)) 
> {
>              fprintf(stderr, "Hardware memory error for memory used by "
>                      "QEMU itself instead of guest system!\n");
> @@ -445,7 +446,8 @@ int kvm_arch_on_sigbus(int code, void *addr)
>          hwaddr paddr;
>
>          /* Hope we are lucky for AO MCE */
> -        if (qemu_ram_addr_from_host(addr, &ram_addr) == NULL ||
> +        ram_addr = qemu_ram_addr_from_host(addr);
> +        if (ram_addr == RAM_ADDR_INVALID ||
>              !kvm_physical_memory_addr_from_host(first_cpu->kvm_state,
>                                                  addr, &paddr)) {
>              fprintf(stderr, "Hardware memory error for memory used by "
> --
> 2.5.5
>
>
>


Reviewed-by: Marc-André Lureau <address@hidden>



-- 
Marc-André Lureau