[Qemu-devel] [PATCH qemu] kvm-all: Align to qemu_real_host_page_size in kvm_set_phys_mem

[Qemu-devel] [PATCH qemu] kvm-all: Align to qemu_real_host_page_size in kvm_set_phys_mem

[Alexey Kardashevskiy]

As the comment in kvm_set_phys_mem() says, KVM works in page size chunks.
However it uses hardcoded TARGET_PAGE_SIZE which is 4K on most platforms
while actual host may use different page size, for example, PPC64 hosts
use 64K system pages.

This replaces static TARGET_PAGE_SIZE with run-time calculated
qemu_real_host_page_size.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---

This is the result of debugging VFIO quirks not working under PPC64 KVM.
---
 kvm-all.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kvm-all.c b/kvm-all.c
index 0be4615..6f04fbb 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -642,15 +642,15 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml,
     /* kvm works in page size chunks, but the function may be called
        with sub-page size and unaligned start address. Pad the start
        address to next and truncate size to previous page boundary. */
-    delta = (TARGET_PAGE_SIZE - (start_addr & ~TARGET_PAGE_MASK));
-    delta &= ~TARGET_PAGE_MASK;
+    delta = qemu_real_host_page_size - (start_addr & ~qemu_real_host_page_mask);
+    delta &= ~qemu_real_host_page_mask;
     if (delta > size) {
         return;
     }
     start_addr += delta;
     size -= delta;
-    size &= TARGET_PAGE_MASK;
-    if (!size || (start_addr & ~TARGET_PAGE_MASK)) {
+    size &= qemu_real_host_page_mask;
+    if (!size || (start_addr & ~qemu_real_host_page_mask)) {
         return;
     }
 
-- 
2.5.0.rc3

Re: [Qemu-devel] [PATCH qemu] kvm-all: Align to qemu_real_host_page_size in kvm_set_phys_mem

[Paolo Bonzini]

On 06/10/2015 05:30, Alexey Kardashevskiy wrote:
> As the comment in kvm_set_phys_mem() says, KVM works in page size chunks.
> However it uses hardcoded TARGET_PAGE_SIZE which is 4K on most platforms
> while actual host may use different page size, for example, PPC64 hosts
> use 64K system pages.
> 
> This replaces static TARGET_PAGE_SIZE with run-time calculated
> qemu_real_host_page_size.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
> 
> This is the result of debugging VFIO quirks not working under PPC64 KVM.
> ---
>  kvm-all.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/kvm-all.c b/kvm-all.c
> index 0be4615..6f04fbb 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -642,15 +642,15 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml,
>      /* kvm works in page size chunks, but the function may be called
>         with sub-page size and unaligned start address. Pad the start
>         address to next and truncate size to previous page boundary. */
> -    delta = (TARGET_PAGE_SIZE - (start_addr & ~TARGET_PAGE_MASK));
> -    delta &= ~TARGET_PAGE_MASK;
> +    delta = qemu_real_host_page_size - (start_addr & ~qemu_real_host_page_mask);
> +    delta &= ~qemu_real_host_page_mask;
>      if (delta > size) {
>          return;
>      }
>      start_addr += delta;
>      size -= delta;
> -    size &= TARGET_PAGE_MASK;
> -    if (!size || (start_addr & ~TARGET_PAGE_MASK)) {
> +    size &= qemu_real_host_page_mask;
> +    if (!size || (start_addr & ~qemu_real_host_page_mask)) {
>          return;
>      }
>  
> 

Queued, thanks.

Paolo