Re: [PATCH v3 09/21] arm64: cpufeature: Add global feature override facility

2021-01-12 Thread Marc Zyngier
On 2021-01-12 11:59, Suzuki K Poulose wrote: On 1/12/21 11:50 AM, Marc Zyngier wrote: Hi Suzuki, On 2021-01-12 09:17, Suzuki K Poulose wrote: Hi Marc, On 1/11/21 7:48 PM, Marc Zyngier wrote: [...] diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index

Re: [PATCH v3 09/21] arm64: cpufeature: Add global feature override facility

2021-01-12 Thread Suzuki K Poulose
On 1/12/21 11:51 AM, Marc Zyngier wrote: On 2021-01-12 11:50, Marc Zyngier wrote: Hi Suzuki, On 2021-01-12 09:17, Suzuki K Poulose wrote: Hi Marc, On 1/11/21 7:48 PM, Marc Zyngier wrote: [...] diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index

Re: [PATCH v3 09/21] arm64: cpufeature: Add global feature override facility

2021-01-12 Thread Suzuki K Poulose
On 1/12/21 11:50 AM, Marc Zyngier wrote: Hi Suzuki, On 2021-01-12 09:17, Suzuki K Poulose wrote: Hi Marc, On 1/11/21 7:48 PM, Marc Zyngier wrote: [...] diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 894af60b9669..00d99e593b65 100644 ---

Re: [PATCH v3 09/21] arm64: cpufeature: Add global feature override facility

2021-01-12 Thread Marc Zyngier
On 2021-01-12 11:50, Marc Zyngier wrote: Hi Suzuki, On 2021-01-12 09:17, Suzuki K Poulose wrote: Hi Marc, On 1/11/21 7:48 PM, Marc Zyngier wrote: [...] diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 894af60b9669..00d99e593b65 100644 ---

Re: [PATCH v3 09/21] arm64: cpufeature: Add global feature override facility

2021-01-12 Thread Marc Zyngier
Hi Suzuki, On 2021-01-12 09:17, Suzuki K Poulose wrote: Hi Marc, On 1/11/21 7:48 PM, Marc Zyngier wrote: [...] diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 894af60b9669..00d99e593b65 100644 --- a/arch/arm64/kernel/cpufeature.c +++

Re: [PATCH v3 09/21] arm64: cpufeature: Add global feature override facility

2021-01-12 Thread Suzuki K Poulose
Hi Marc, On 1/11/21 7:48 PM, Marc Zyngier wrote: Hi Catalin, On 2021-01-11 18:41, Catalin Marinas wrote: Hi Marc, On Mon, Jan 11, 2021 at 01:27:59PM +, Marc Zyngier wrote: Add a facility to globally override a feature, no matter what the HW says. Yes, this is dangerous. Yeah, it's

Re: [PATCH v3 09/21] arm64: cpufeature: Add global feature override facility

2021-01-11 Thread Srinivas Ramana
Hi Catalin, On 1/11/2021 10:41 AM, Catalin Marinas wrote: Hi Marc, On Mon, Jan 11, 2021 at 01:27:59PM +, Marc Zyngier wrote: Add a facility to globally override a feature, no matter what the HW says. Yes, this is dangerous. Yeah, it's dangerous. We can make it less so if we only allow

Re: [PATCH v3 09/21] arm64: cpufeature: Add global feature override facility

2021-01-11 Thread Marc Zyngier
Hi Catalin, On 2021-01-11 18:41, Catalin Marinas wrote: Hi Marc, On Mon, Jan 11, 2021 at 01:27:59PM +, Marc Zyngier wrote: Add a facility to globally override a feature, no matter what the HW says. Yes, this is dangerous. Yeah, it's dangerous. We can make it less so if we only allow

Re: [PATCH v3 09/21] arm64: cpufeature: Add global feature override facility

2021-01-11 Thread Catalin Marinas
Hi Marc, On Mon, Jan 11, 2021 at 01:27:59PM +, Marc Zyngier wrote: > Add a facility to globally override a feature, no matter what > the HW says. Yes, this is dangerous. Yeah, it's dangerous. We can make it less so if we only allow safe values (e.g. lower if FTR_UNSIGNED). > diff --git

[PATCH v3 09/21] arm64: cpufeature: Add global feature override facility

2021-01-11 Thread Marc Zyngier
Add a facility to globally override a feature, no matter what the HW says. Yes, this is dangerous. Nothing uses this yet, so we are pretty safe. For now. Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/cpufeature.h | 2 ++ arch/arm64/kernel/cpufeature.c | 26