Do not switch kvm_mode to KVM_MODE_PROTECTED if hypervisor mode is not
available. This prevents "Protected KVM" cpu capability being reported
when Linux is booting in EL1 and would not have KVM enabled.
Signed-off-by: Elliot Berman <[email protected]>
---
arch/arm64/kvm/arm.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 8fe73ee5fa84..861f4b388879 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -2272,7 +2272,9 @@ static int __init early_kvm_mode_cfg(char *arg)
return -EINVAL;
if (strcmp(arg, "protected") == 0) {
- if (!is_kernel_in_hyp_mode())
+ if (!is_hyp_mode_available())
+ kvm_mode = KVM_MODE_DEFAULT;
+ else if (!is_kernel_in_hyp_mode())
kvm_mode = KVM_MODE_PROTECTED;
else
pr_warn_once("Protected KVM not available with VHE\n");
base-commit: 0982c8d859f8f7022b9fd44d421c7ec721bb41f9
--
2.25.1
On Fri, Sep 09, 2022 at 07:45:52AM -0700, Elliot Berman wrote:
> Do not switch kvm_mode to KVM_MODE_PROTECTED if hypervisor mode is not
> available. This prevents "Protected KVM" cpu capability being reported
> when Linux is booting in EL1 and would not have KVM enabled.
>
> Signed-off-by: Elliot Berman <[email protected]>
> ---
> arch/arm64/kvm/arm.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 8fe73ee5fa84..861f4b388879 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -2272,7 +2272,9 @@ static int __init early_kvm_mode_cfg(char *arg)
> return -EINVAL;
>
> if (strcmp(arg, "protected") == 0) {
> - if (!is_kernel_in_hyp_mode())
> + if (!is_hyp_mode_available())
> + kvm_mode = KVM_MODE_DEFAULT;
I think kvm_mode is already KVM_MODE_DEFAULT at this point. You may want
to print a warning instead.
--
Catalin
On 9/9/2022 10:28 AM, Catalin Marinas wrote:
> On Fri, Sep 09, 2022 at 07:45:52AM -0700, Elliot Berman wrote:
>> Do not switch kvm_mode to KVM_MODE_PROTECTED if hypervisor mode is not
>> available. This prevents "Protected KVM" cpu capability being reported
>> when Linux is booting in EL1 and would not have KVM enabled.
>>
>> Signed-off-by: Elliot Berman <[email protected]>
>> ---
>> arch/arm64/kvm/arm.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
>> index 8fe73ee5fa84..861f4b388879 100644
>> --- a/arch/arm64/kvm/arm.c
>> +++ b/arch/arm64/kvm/arm.c
>> @@ -2272,7 +2272,9 @@ static int __init early_kvm_mode_cfg(char *arg)
>> return -EINVAL;
>>
>> if (strcmp(arg, "protected") == 0) {
>> - if (!is_kernel_in_hyp_mode())
>> + if (!is_hyp_mode_available())
>> + kvm_mode = KVM_MODE_DEFAULT;
>
> I think kvm_mode is already KVM_MODE_DEFAULT at this point. You may want
> to print a warning instead.
>
Does it make sense to print warning for kvm-arm.mode=nvhe as well?
On Sat, Sep 10, 2022 at 10:09:31AM +0100, Marc Zyngier wrote:
> On Fri, 09 Sep 2022 18:55:18 +0100,
> Elliot Berman <[email protected]> wrote:
> >
> >
> >
> > On 9/9/2022 10:28 AM, Catalin Marinas wrote:
> > > On Fri, Sep 09, 2022 at 07:45:52AM -0700, Elliot Berman wrote:
> > >> Do not switch kvm_mode to KVM_MODE_PROTECTED if hypervisor mode is not
> > >> available. This prevents "Protected KVM" cpu capability being reported
> > >> when Linux is booting in EL1 and would not have KVM enabled.
> > >>
> > >> Signed-off-by: Elliot Berman <[email protected]>
> > >> ---
> > >> arch/arm64/kvm/arm.c | 4 +++-
> > >> 1 file changed, 3 insertions(+), 1 deletion(-)
> > >>
> > >> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> > >> index 8fe73ee5fa84..861f4b388879 100644
> > >> --- a/arch/arm64/kvm/arm.c
> > >> +++ b/arch/arm64/kvm/arm.c
> > >> @@ -2272,7 +2272,9 @@ static int __init early_kvm_mode_cfg(char *arg)
> > >> return -EINVAL;
> > >> if (strcmp(arg, "protected") == 0) {
> > >> - if (!is_kernel_in_hyp_mode())
> > >> + if (!is_hyp_mode_available())
> > >> + kvm_mode = KVM_MODE_DEFAULT;
> > >
> > > I think kvm_mode is already KVM_MODE_DEFAULT at this point. You may want
> > > to print a warning instead.
> > >
> >
> > Does it make sense to print warning for kvm-arm.mode=nvhe as well?
>
> In general, specifying a kvm-arm.mode when no hypervisor mode is
> available should be reported as a warning.
As long as this is pr_warn() rather than WARN() then I agree. Otherwise,
kernels with a kvm-arm.mode hardcoded in CONFIG_CMDLINE (e.g. Android's
GKI) will make for noisy guests.
Will
On Sat, 10 Sep 2022 14:43:44 +0100,
Will Deacon <[email protected]> wrote:
>
> On Sat, Sep 10, 2022 at 10:09:31AM +0100, Marc Zyngier wrote:
> > On Fri, 09 Sep 2022 18:55:18 +0100,
> > Elliot Berman <[email protected]> wrote:
> > >
> > >
> > >
> > > On 9/9/2022 10:28 AM, Catalin Marinas wrote:
> > > > On Fri, Sep 09, 2022 at 07:45:52AM -0700, Elliot Berman wrote:
> > > >> Do not switch kvm_mode to KVM_MODE_PROTECTED if hypervisor mode is not
> > > >> available. This prevents "Protected KVM" cpu capability being reported
> > > >> when Linux is booting in EL1 and would not have KVM enabled.
> > > >>
> > > >> Signed-off-by: Elliot Berman <[email protected]>
> > > >> ---
> > > >> arch/arm64/kvm/arm.c | 4 +++-
> > > >> 1 file changed, 3 insertions(+), 1 deletion(-)
> > > >>
> > > >> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> > > >> index 8fe73ee5fa84..861f4b388879 100644
> > > >> --- a/arch/arm64/kvm/arm.c
> > > >> +++ b/arch/arm64/kvm/arm.c
> > > >> @@ -2272,7 +2272,9 @@ static int __init early_kvm_mode_cfg(char *arg)
> > > >> return -EINVAL;
> > > >> if (strcmp(arg, "protected") == 0) {
> > > >> - if (!is_kernel_in_hyp_mode())
> > > >> + if (!is_hyp_mode_available())
> > > >> + kvm_mode = KVM_MODE_DEFAULT;
> > > >
> > > > I think kvm_mode is already KVM_MODE_DEFAULT at this point. You may want
> > > > to print a warning instead.
> > > >
> > >
> > > Does it make sense to print warning for kvm-arm.mode=nvhe as well?
> >
> > In general, specifying a kvm-arm.mode when no hypervisor mode is
> > available should be reported as a warning.
>
> As long as this is pr_warn() rather than WARN() then I agree. Otherwise,
> kernels with a kvm-arm.mode hardcoded in CONFIG_CMDLINE (e.g. Android's
> GKI) will make for noisy guests.
Indeed, pr_warn() is what I had in mind. A WARN() would be pretty
overkill, as there is nothing majorly wrong with booting at EL1, just
an impossibility to honour the request from the command line.
M.
--
Without deviation from the norm, progress is not possible.