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softmmu/physmem: Introduce MemTxAttrs::memory field and MEMTX_ACCESS_ERROR

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Add the 'memory' bit to the memory attributes to restrict bus
controller accesses to memories.

Introduce flatview_access_allowed() to check bus permission
before running any bus transaction.

Have read/write accessors return MEMTX_ACCESS_ERROR if an access is
restricted.

There is no change for the default case where 'memory' is not set.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20211215182421.418374-4-philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
[thuth: Replaced MEMTX_BUS_ERROR with MEMTX_ACCESS_ERROR, remove "inline"]
Signed-off-by: Thomas Huth <thuth@redhat.com>
This commit is contained in:
Philippe Mathieu-Daudé 2021-12-15 19:24:21 +01:00 committed by Thomas Huth
parent 58e74682ba
commit 3ab6fdc91b
2 changed files with 51 additions and 2 deletions
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9
include/exec/memattrs.h
View File

@ -35,6 +35,14 @@ typedef struct MemTxAttrs {
unsigned int secure:1;
/* Memory access is usermode (unprivileged) */
unsigned int user:1;
/*
* Bus interconnect and peripherals can access anything (memories,
* devices) by default. By setting the 'memory' bit, bus transaction
* are restricted to "normal" memories (per the AMBA documentation)
* versus devices. Access to devices will be logged and rejected
* (see MEMTX_ACCESS_ERROR).
*/
unsigned int memory:1;
/* Requester ID (for MSI for example) */
unsigned int requester_id:16;
/* Invert endianness for this page */
@ -66,6 +74,7 @@ typedef struct MemTxAttrs {
#define MEMTX_OK 0
#define MEMTX_ERROR (1U << 0) /* device returned an error */
#define MEMTX_DECODE_ERROR (1U << 1) /* nothing at that address */
#define MEMTX_ACCESS_ERROR (1U << 2) /* access denied */
typedef uint32_t MemTxResult;
#endif

44
softmmu/physmem.c
View File

@ -42,6 +42,7 @@
#include "qemu/config-file.h"
#include "qemu/error-report.h"
#include "qemu/qemu-print.h"
#include "qemu/log.h"
#include "qemu/memalign.h"
#include "exec/memory.h"
#include "exec/ioport.h"
@ -2760,6 +2761,33 @@ static bool prepare_mmio_access(MemoryRegion *mr)
return release_lock;
}
/**
* flatview_access_allowed
* @mr: #MemoryRegion to be accessed
* @attrs: memory transaction attributes
* @addr: address within that memory region
* @len: the number of bytes to access
*
* Check if a memory transaction is allowed.
*
* Returns: true if transaction is allowed, false if denied.
*/
static bool flatview_access_allowed(MemoryRegion *mr, MemTxAttrs attrs,
hwaddr addr, hwaddr len)
{
if (likely(!attrs.memory)) {
return true;
}
if (memory_region_is_ram(mr)) {
return true;
}
qemu_log_mask(LOG_GUEST_ERROR,
"Invalid access to non-RAM device at "
"addr 0x%" HWADDR_PRIX ", size %" HWADDR_PRIu ", "
"region '%s'\n", addr, len, memory_region_name(mr));
return false;
}
/* Called within RCU critical section. */
static MemTxResult flatview_write_continue(FlatView *fv, hwaddr addr,
MemTxAttrs attrs,
@ -2774,7 +2802,10 @@ static MemTxResult flatview_write_continue(FlatView *fv, hwaddr addr,
const uint8_t *buf = ptr;
for (;;) {
if (!memory_access_is_direct(mr, true)) {
if (!flatview_access_allowed(mr, attrs, addr1, l)) {
result |= MEMTX_ACCESS_ERROR;
/* Keep going. */
} else if (!memory_access_is_direct(mr, true)) {
release_lock |= prepare_mmio_access(mr);
l = memory_access_size(mr, l, addr1);
/* XXX: could force current_cpu to NULL to avoid
@ -2819,6 +2850,9 @@ static MemTxResult flatview_write(FlatView *fv, hwaddr addr, MemTxAttrs attrs,
l = len;
mr = flatview_translate(fv, addr, &addr1, &l, true, attrs);
if (!flatview_access_allowed(mr, attrs, addr, len)) {
return MEMTX_ACCESS_ERROR;
}
return flatview_write_continue(fv, addr, attrs, buf, len,
addr1, l, mr);
}
@ -2837,7 +2871,10 @@ MemTxResult flatview_read_continue(FlatView *fv, hwaddr addr,
fuzz_dma_read_cb(addr, len, mr);
for (;;) {
if (!memory_access_is_direct(mr, false)) {
if (!flatview_access_allowed(mr, attrs, addr1, l)) {
result |= MEMTX_ACCESS_ERROR;
/* Keep going. */
} else if (!memory_access_is_direct(mr, false)) {
/* I/O case */
release_lock |= prepare_mmio_access(mr);
l = memory_access_size(mr, l, addr1);
@ -2880,6 +2917,9 @@ static MemTxResult flatview_read(FlatView *fv, hwaddr addr,
l = len;
mr = flatview_translate(fv, addr, &addr1, &l, false, attrs);
if (!flatview_access_allowed(mr, attrs, addr, len)) {
return MEMTX_ACCESS_ERROR;
}
return flatview_read_continue(fv, addr, attrs, buf, len,
addr1, l, mr);
}