Re: [RFC PATCH v2 4/5] softmmu/physmem: Introduce flatview_access_allowed() to check bus perms
On Mon, Aug 23, 2021 at 06:41:56PM +0200, Philippe Mathieu-Daudé wrote:
> Introduce flatview_access_allowed() to check bus permission
> before running any bus transaction. For now this is a simple
> stub.
>
> Signed-off-by: Philippe Mathieu-Daudé
> ---
> softmmu/physmem.c | 37 +++--
> 1 file changed, 35 insertions(+), 2 deletions(-)
>
> diff --git a/softmmu/physmem.c b/softmmu/physmem.c
> index e534dc69918..0d31a2f4199 100644
> --- a/softmmu/physmem.c
> +++ b/softmmu/physmem.c
> @@ -2754,6 +2754,27 @@ 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
> + * @result: optional pointer to a MemTxResult or NULL
> + *
> + * Check if a memory transaction is allowed. If an error occurs this
> + * method will return false to indicate denial, as well as setting
> + * @result to contain corresponding #MemTxResult.
> + *
> + * Returns: true if transaction is allowed, false if denied.
> + */
> +static inline bool flatview_access_allowed(MemoryRegion *mr, MemTxAttrs
> attrs,
> + hwaddr addr, hwaddr len,
> + MemTxResult *result)
> +{
> +return true;
> +}
The callers below don't benefit from the result pointer argument. The
code would be clearer if they did:
if (!flatview_access_allowed(...)) {
return MEMTX_BUS_ERROR;
}
> +
> /* Called within RCU critical section. */
> static MemTxResult flatview_write_continue(FlatView *fv, hwaddr addr,
> MemTxAttrs attrs,
> @@ -2768,7 +2789,9 @@ 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' contains the 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
> @@ -2810,9 +2833,13 @@ static MemTxResult flatview_write(FlatView *fv, hwaddr
> addr, MemTxAttrs attrs,
> hwaddr l;
> hwaddr addr1;
> MemoryRegion *mr;
> +MemTxResult result = MEMTX_OK;
>
> l = len;
> mr = flatview_translate(fv, addr, , , true, attrs);
> +if (!flatview_access_allowed(mr, attrs, addr, len, )) {
> +return result;
> +}
> return flatview_write_continue(fv, addr, attrs, buf, len,
> addr1, l, mr);
> }
> @@ -2831,7 +2858,9 @@ 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' contains the 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);
> @@ -2871,9 +2900,13 @@ static MemTxResult flatview_read(FlatView *fv, hwaddr
> addr,
> hwaddr l;
> hwaddr addr1;
> MemoryRegion *mr;
> +MemTxResult result = MEMTX_OK;
>
> l = len;
> mr = flatview_translate(fv, addr, , , false, attrs);
> +if (!flatview_access_allowed(mr, attrs, addr, len, )) {
> +return result;
> +}
> return flatview_read_continue(fv, addr, attrs, buf, len,
>addr1, l, mr);
> }
> --
> 2.31.1
>
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Re: [RFC PATCH v2 4/5] softmmu/physmem: Introduce flatview_access_allowed() to check bus perms
On 23.08.21 20:43, Peter Xu wrote: On Mon, Aug 23, 2021 at 06:41:56PM +0200, Philippe Mathieu-Daudé wrote: Introduce flatview_access_allowed() to check bus permission before running any bus transaction. For now this is a simple stub. Signed-off-by: Philippe Mathieu-Daudé Shall we squash this patch into the next one? It helps explain better on why it's needed. Thanks, I'd even go one step further and squash 3-5 into a single one. -- Thanks, David / dhildenb
Re: [RFC PATCH v2 4/5] softmmu/physmem: Introduce flatview_access_allowed() to check bus perms
On Mon, Aug 23, 2021 at 06:41:56PM +0200, Philippe Mathieu-Daudé wrote: > Introduce flatview_access_allowed() to check bus permission > before running any bus transaction. For now this is a simple > stub. > > Signed-off-by: Philippe Mathieu-Daudé Shall we squash this patch into the next one? It helps explain better on why it's needed. Thanks, -- Peter Xu
[RFC PATCH v2 4/5] softmmu/physmem: Introduce flatview_access_allowed() to check bus perms
Introduce flatview_access_allowed() to check bus permission
before running any bus transaction. For now this is a simple
stub.
Signed-off-by: Philippe Mathieu-Daudé
---
softmmu/physmem.c | 37 +++--
1 file changed, 35 insertions(+), 2 deletions(-)
diff --git a/softmmu/physmem.c b/softmmu/physmem.c
index e534dc69918..0d31a2f4199 100644
--- a/softmmu/physmem.c
+++ b/softmmu/physmem.c
@@ -2754,6 +2754,27 @@ 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
+ * @result: optional pointer to a MemTxResult or NULL
+ *
+ * Check if a memory transaction is allowed. If an error occurs this
+ * method will return false to indicate denial, as well as setting
+ * @result to contain corresponding #MemTxResult.
+ *
+ * Returns: true if transaction is allowed, false if denied.
+ */
+static inline bool flatview_access_allowed(MemoryRegion *mr, MemTxAttrs attrs,
+ hwaddr addr, hwaddr len,
+ MemTxResult *result)
+{
+return true;
+}
+
/* Called within RCU critical section. */
static MemTxResult flatview_write_continue(FlatView *fv, hwaddr addr,
MemTxAttrs attrs,
@@ -2768,7 +2789,9 @@ 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' contains the 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
@@ -2810,9 +2833,13 @@ static MemTxResult flatview_write(FlatView *fv, hwaddr
addr, MemTxAttrs attrs,
hwaddr l;
hwaddr addr1;
MemoryRegion *mr;
+MemTxResult result = MEMTX_OK;
l = len;
mr = flatview_translate(fv, addr, , , true, attrs);
+if (!flatview_access_allowed(mr, attrs, addr, len, )) {
+return result;
+}
return flatview_write_continue(fv, addr, attrs, buf, len,
addr1, l, mr);
}
@@ -2831,7 +2858,9 @@ 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' contains the 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);
@@ -2871,9 +2900,13 @@ static MemTxResult flatview_read(FlatView *fv, hwaddr
addr,
hwaddr l;
hwaddr addr1;
MemoryRegion *mr;
+MemTxResult result = MEMTX_OK;
l = len;
mr = flatview_translate(fv, addr, , , false, attrs);
+if (!flatview_access_allowed(mr, attrs, addr, len, )) {
+return result;
+}
return flatview_read_continue(fv, addr, attrs, buf, len,
addr1, l, mr);
}
--
2.31.1
