Performant CXL type 3 non-interleaved regions

[PATCH v2 1/2] hw/cxl: Use HPA in cxl_cfmws_find_device() rather than offset in window.

Posted by Alireza Sanaee via qemu development 5 days, 4 hours ago

This function will shortly be used to help find if there is a route to a
device, serving an HPA, under a particular fixed memory window. Rather
than having that new use case subtract the base address in the caller,
only to add it again in cxl_cfmws_find_device(), push the responsibility
for calculating the HPA to the caller.

This also reduces the inconsistency in the meaning of the hwaddr
addr parameter between this function and the calls made within it
that access the HDM decoders that operating on HPA.

Signed-off-by: Alireza Sanaee <alireza.sanaee@huawei.com>
---
 hw/cxl/cxl-host.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/hw/cxl/cxl-host.c b/hw/cxl/cxl-host.c
index f3479b1991..9633b01abf 100644
--- a/hw/cxl/cxl-host.c
+++ b/hw/cxl/cxl-host.c
@@ -168,8 +168,6 @@ static PCIDevice *cxl_cfmws_find_device(CXLFixedWindow *fw, hwaddr addr)
     bool target_found;
     PCIDevice *rp, *d;
 
-    /* Address is relative to memory region. Convert to HPA */
-    addr += fw->base;
 
     rb_index = (addr / cxl_decode_ig(fw->enc_int_gran)) % fw->num_targets;
     hb = PCI_HOST_BRIDGE(fw->target_hbs[rb_index]->cxl_host_bridge);
@@ -254,7 +252,7 @@ static MemTxResult cxl_read_cfmws(void *opaque, hwaddr addr, uint64_t *data,
     CXLFixedWindow *fw = opaque;
     PCIDevice *d;
 
-    d = cxl_cfmws_find_device(fw, addr);
+    d = cxl_cfmws_find_device(fw, addr + fw->base, true);
     if (d == NULL) {
         *data = 0;
         /* Reads to invalid address return poison */
@@ -271,7 +269,7 @@ static MemTxResult cxl_write_cfmws(void *opaque, hwaddr addr,
     CXLFixedWindow *fw = opaque;
     PCIDevice *d;
 
-    d = cxl_cfmws_find_device(fw, addr);
+    d = cxl_cfmws_find_device(fw, addr + fw->base, true);
     if (d == NULL) {
         /* Writes to invalid address are silent */
         return MEMTX_OK;
-- 
2.43.0

Re: [PATCH v2 1/2] hw/cxl: Use HPA in cxl_cfmws_find_device() rather than offset in window.

Posted by Zhijian Li (Fujitsu) 3 days, 10 hours ago


On 04/02/2026 23:00, Alireza Sanaee wrote:
> This function will shortly be used to help find if there is a route to a
> device, serving an HPA, under a particular fixed memory window. Rather
> than having that new use case subtract the base address in the caller,
> only to add it again in cxl_cfmws_find_device(), push the responsibility
> for calculating the HPA to the caller.
> 
> This also reduces the inconsistency in the meaning of the hwaddr
> addr parameter between this function and the calls made within it
> that access the HDM decoders that operating on HPA.
> 
> Signed-off-by: Alireza Sanaee <alireza.sanaee@huawei.com>
> ---
>   hw/cxl/cxl-host.c | 6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/cxl/cxl-host.c b/hw/cxl/cxl-host.c
> index f3479b1991..9633b01abf 100644
> --- a/hw/cxl/cxl-host.c
> +++ b/hw/cxl/cxl-host.c
> @@ -168,8 +168,6 @@ static PCIDevice *cxl_cfmws_find_device(CXLFixedWindow *fw, hwaddr addr)
>       bool target_found;
>       PCIDevice *rp, *d;
>   
> -    /* Address is relative to memory region. Convert to HPA */
> -    addr += fw->base;
>   
>       rb_index = (addr / cxl_decode_ig(fw->enc_int_gran)) % fw->num_targets;
>       hb = PCI_HOST_BRIDGE(fw->target_hbs[rb_index]->cxl_host_bridge);
> @@ -254,7 +252,7 @@ static MemTxResult cxl_read_cfmws(void *opaque, hwaddr addr, uint64_t *data,
>       CXLFixedWindow *fw = opaque;
>       PCIDevice *d;
>   
> -    d = cxl_cfmws_find_device(fw, addr);
> +    d = cxl_cfmws_find_device(fw, addr + fw->base, true);


It seems you've added an extra parameter to the calls to cxl_cfmws_find_device(), but its function signature wasn't updated.



Thanks
Zhijian



>       if (d == NULL) {
>           *data = 0;
>           /* Reads to invalid address return poison */
> @@ -271,7 +269,7 @@ static MemTxResult cxl_write_cfmws(void *opaque, hwaddr addr,
>       CXLFixedWindow *fw = opaque;
>       PCIDevice *d;
>   
> -    d = cxl_cfmws_find_device(fw, addr);
> +    d = cxl_cfmws_find_device(fw, addr + fw->base, true);
>       if (d == NULL) {
>           /* Writes to invalid address are silent */
>           return MEMTX_OK;

Re: [PATCH v2 1/2] hw/cxl: Use HPA in cxl_cfmws_find_device() rather than offset in window.

Posted by Jonathan Cameron via qemu development 3 days, 7 hours ago

On Fri, 6 Feb 2026 09:57:15 +0000
"Zhijian Li (Fujitsu)" <lizhijian@fujitsu.com> wrote:

> On 04/02/2026 23:00, Alireza Sanaee wrote:
> > This function will shortly be used to help find if there is a route to a
> > device, serving an HPA, under a particular fixed memory window. Rather
> > than having that new use case subtract the base address in the caller,
> > only to add it again in cxl_cfmws_find_device(), push the responsibility
> > for calculating the HPA to the caller.
> > 
> > This also reduces the inconsistency in the meaning of the hwaddr
> > addr parameter between this function and the calls made within it
> > that access the HDM decoders that operating on HPA.
> > 
> > Signed-off-by: Alireza Sanaee <alireza.sanaee@huawei.com>
> > ---
> >   hw/cxl/cxl-host.c | 6 ++----
> >   1 file changed, 2 insertions(+), 4 deletions(-)
> > 
> > diff --git a/hw/cxl/cxl-host.c b/hw/cxl/cxl-host.c
> > index f3479b1991..9633b01abf 100644
> > --- a/hw/cxl/cxl-host.c
> > +++ b/hw/cxl/cxl-host.c
> > @@ -168,8 +168,6 @@ static PCIDevice *cxl_cfmws_find_device(CXLFixedWindow *fw, hwaddr addr)
> >       bool target_found;
> >       PCIDevice *rp, *d;
> >   
> > -    /* Address is relative to memory region. Convert to HPA */
> > -    addr += fw->base;
> >   
> >       rb_index = (addr / cxl_decode_ig(fw->enc_int_gran)) % fw->num_targets;
> >       hb = PCI_HOST_BRIDGE(fw->target_hbs[rb_index]->cxl_host_bridge);
> > @@ -254,7 +252,7 @@ static MemTxResult cxl_read_cfmws(void *opaque, hwaddr addr, uint64_t *data,
> >       CXLFixedWindow *fw = opaque;
> >       PCIDevice *d;
> >   
> > -    d = cxl_cfmws_find_device(fw, addr);
> > +    d = cxl_cfmws_find_device(fw, addr + fw->base, true);  
> 
> 
> It seems you've added an extra parameter to the calls to cxl_cfmws_find_device(), but its function signature wasn't updated.

Good spot. The extra parameter should be in the next patch.

Jonathan

> 
> 
> 
> Thanks
> Zhijian
> 
> 
> 
> >       if (d == NULL) {
> >           *data = 0;
> >           /* Reads to invalid address return poison */
> > @@ -271,7 +269,7 @@ static MemTxResult cxl_write_cfmws(void *opaque, hwaddr addr,
> >       CXLFixedWindow *fw = opaque;
> >       PCIDevice *d;
> >   
> > -    d = cxl_cfmws_find_device(fw, addr);
> > +    d = cxl_cfmws_find_device(fw, addr + fw->base, true);
> >       if (d == NULL) {
> >           /* Writes to invalid address are silent */
> >           return MEMTX_OK;