[v1] TDX support

[RFC PATCH 02/23] kvm: Switch KVM_CAP_READONLY_MEM to a per-VM ioctl()

Posted by Isaku Yamahata 4 years, 9 months ago

Switch to making a VM ioctl() call for KVM_CAP_READONLY_MEM, which may
be conditional on VM type in recent versions of KVM, e.g. when TDX is
supported.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
 accel/kvm/kvm-all.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 47516913b7..351c25a5cb 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2164,7 +2164,7 @@ static int kvm_init(MachineState *ms)
     }
 
     kvm_readonly_mem_allowed =
-        (kvm_check_extension(s, KVM_CAP_READONLY_MEM) > 0);
+        (kvm_vm_check_extension(s, KVM_CAP_READONLY_MEM) > 0);
 
     kvm_eventfds_allowed =
         (kvm_check_extension(s, KVM_CAP_IOEVENTFD) > 0);
-- 
2.17.1

Re: [RFC PATCH 02/23] kvm: Switch KVM_CAP_READONLY_MEM to a per-VM ioctl()

Posted by Philippe Mathieu-Daudé 4 years, 9 months ago

Hi Isaku,

On 2/16/21 3:12 AM, Isaku Yamahata wrote:
> Switch to making a VM ioctl() call for KVM_CAP_READONLY_MEM, which may
> be conditional on VM type in recent versions of KVM, e.g. when TDX is
> supported.
> 
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---
>  accel/kvm/kvm-all.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index 47516913b7..351c25a5cb 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -2164,7 +2164,7 @@ static int kvm_init(MachineState *ms)
>      }
>  
>      kvm_readonly_mem_allowed =
> -        (kvm_check_extension(s, KVM_CAP_READONLY_MEM) > 0);
> +        (kvm_vm_check_extension(s, KVM_CAP_READONLY_MEM) > 0);

Can this check with "recent KVM" be a problem with older ones?

Maybe for backward compatibility we need:

          = (kvm_vm_check_extension(s, KVM_CAP_READONLY_MEM) > 0) ||
            (kvm_check_extension(s, KVM_CAP_READONLY_MEM) > 0);

>      kvm_eventfds_allowed =
>          (kvm_check_extension(s, KVM_CAP_IOEVENTFD) > 0);
>

Re: [RFC PATCH 02/23] kvm: Switch KVM_CAP_READONLY_MEM to a per-VM ioctl()

Posted by Isaku Yamahata 4 years, 8 months ago

On Tue, Feb 16, 2021 at 08:56:45AM +0100,
Philippe Mathieu-Daudé <philmd@redhat.com> wrote:

> Hi Isaku,
> 
> On 2/16/21 3:12 AM, Isaku Yamahata wrote:
> > Switch to making a VM ioctl() call for KVM_CAP_READONLY_MEM, which may
> > be conditional on VM type in recent versions of KVM, e.g. when TDX is
> > supported.
> > 
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> > ---
> >  accel/kvm/kvm-all.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> > index 47516913b7..351c25a5cb 100644
> > --- a/accel/kvm/kvm-all.c
> > +++ b/accel/kvm/kvm-all.c
> > @@ -2164,7 +2164,7 @@ static int kvm_init(MachineState *ms)
> >      }
> >  
> >      kvm_readonly_mem_allowed =
> > -        (kvm_check_extension(s, KVM_CAP_READONLY_MEM) > 0);
> > +        (kvm_vm_check_extension(s, KVM_CAP_READONLY_MEM) > 0);
> 
> Can this check with "recent KVM" be a problem with older ones?
> 
> Maybe for backward compatibility we need:
> 
>           = (kvm_vm_check_extension(s, KVM_CAP_READONLY_MEM) > 0) ||
>             (kvm_check_extension(s, KVM_CAP_READONLY_MEM) > 0);

Agreed. That's safer and it's difficult to check the very old version of kenel
and non-x86 arch.

Thanks,

-- 
Isaku Yamahata <isaku.yamahata@gmail.com>