On Mon, Nov 14, 2016 at 11:35:08AM +1100, Suraj Jitindar Singh wrote:
> The function kvmppc_set_arch_compat() is used to determine the value of the
> processor compatibility register (PCR) for a guest running in a given
> compatibility mode. There is currently no support for v3.00 of the ISA.
>
> Add support for v3.00 of the ISA which adds an ISA v2.07 compatilibity mode
> to the PCR.
>
> We also add a check to ensure the processor we are running on is capable of
> emulating the chosen processor (for example a POWER7 cannot emulate a
> POWER8, similarly with a POWER8 and a POWER9).
>
> Based on work by: Paul Mackerras <pau...@samba.org>
>
> Signed-off-by: Suraj Jitindar Singh <sjitindarsi...@gmail.com>
> ---
> arch/powerpc/kvm/book3s_hv.c | 38 +++++++++++++++++++++++---------------
> 1 file changed, 23 insertions(+), 15 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 3686471..5d83ecb 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -301,39 +301,47 @@ static void kvmppc_set_pvr_hv(struct kvm_vcpu *vcpu,
> u32 pvr)
I would suggest adding here:
/* Dummy value to be used until a successor to POWER9 appears */
#define PCR_ARCH_300 (PCR_ARCH_207 << 1)
> static int kvmppc_set_arch_compat(struct kvm_vcpu *vcpu, u32 arch_compat)
> {
> - unsigned long pcr = 0;
> + unsigned long host_pcr_bit = 0, guest_pcr_bit = 0;
> struct kvmppc_vcore *vc = vcpu->arch.vcore;
>
> + /* We can (emulate) our own architecture version and anything older */
> + if (cpu_has_feature(CPU_FTR_ARCH_300))
> + host_pcr_bit = PCR_ARCH_300;
> + else if (cpu_has_feature(CPU_FTR_ARCH_207S))
> + host_pcr_bit = PCR_ARCH_207;
> + else if (cpu_has_feature(CPU_FTR_ARCH_206))
> + host_pcr_bit = PCR_ARCH_206;
> + else
> + host_pcr_bit = PCR_ARCH_205;
I don't think you need this last case because we refuse to run on any
CPU that doesn't at least have CPU_FTR_ARCH_206 - see
kvmppc_core_check_processor_compat_hv().
> +
> + /* Determine lowest PCR bit needed to run guest in given PVR level */
> if (arch_compat) {
> switch (arch_compat) {
> case PVR_ARCH_205:
> - /*
> - * If an arch bit is set in PCR, all the defined
> - * higher-order arch bits also have to be set.
> - */
> - pcr = PCR_ARCH_206 | PCR_ARCH_205;
> + guest_pcr_bit = PCR_ARCH_205;
> break;
> case PVR_ARCH_206:
> case PVR_ARCH_206p:
> - pcr = PCR_ARCH_206;
> + guest_pcr_bit = PCR_ARCH_206;
> break;
> case PVR_ARCH_207:
> + guest_pcr_bit = PCR_ARCH_207;
> + break;
> + case PVR_ARCH_300:
> + guest_pcr_bit = PCR_ARCH_300;
> break;
> default:
> return -EINVAL;
> }
> -
> - if (!cpu_has_feature(CPU_FTR_ARCH_207S)) {
> - /* POWER7 can't emulate POWER8 */
> - if (!(pcr & PCR_ARCH_206))
> - return -EINVAL;
> - pcr &= ~PCR_ARCH_206;
> - }
> }
>
> + /* Check requested PCR bits don't exceed our capabilities */
> + if (guest_pcr_bit > host_pcr_bit)
> + return -EINVAL;
> +
> spin_lock(&vc->lock);
> vc->arch_compat = arch_compat;
> - vc->pcr = pcr;
> + vc->pcr = host_pcr_bit - guest_pcr_bit;
This is probably worth a comment. Something like "This sets each bit
for which guest_pcr_bit <= bit < host_pcr_bit."
Paul.
