Re: [PATCH v1 5/9] Add RDT device interface through MSRs

[Jonathan Cameron via <qemu-devel@nongnu.org>]

On Fri, 19 Jul 2024 16:29:25 +0000
Hendrik Wuethrich <whendrik@google.com> wrote:

> From: ‪Hendrik Wüthrich <whendrik@google.com>
> 
> Implement rdmsr and wrmsr for the following MSRs:
> * MSR_IA32_PQR_ASSOC
> * MSR_IA32_QM_EVTSEL
> * MSR_IA32_QM_CTR
> * IA32_L3_QOS_Mask_n
> * IA32_L2_QOS_Mask_n
> * IA32_L2_QoS_Ext_BW_Thrtl_n
> 
> This allows for the guest to call RDT-internal functions to
> associate an RMID with a CLOSID / set an active RMID for
> monitoring, read monitoring data, and set classes of service.
> 
> Signed-off-by: Hendrik Wüthrich <whendrik@google.com>
A few comments inline. Mostly code cleanup stuff.

> ---
>  hw/i386/rdt.c                        |  8 +++
>  include/hw/i386/rdt.h                |  8 ++-
>  target/i386/cpu.h                    | 14 +++++
>  target/i386/tcg/sysemu/misc_helper.c | 80 ++++++++++++++++++++++++++++
>  4 files changed, 109 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/i386/rdt.c b/hw/i386/rdt.c
> index 77b7b4f2d4..0d0e5751fc 100644
> --- a/hw/i386/rdt.c
> +++ b/hw/i386/rdt.c
> @@ -17,6 +17,10 @@
>  #define MAX_L2_MASK_COUNT      48
>  #define MAX_MBA_THRTL_COUNT    31
>  
> +#define CPUID_10_1_EDX_COS_MAX          MAX_L3_MASK_COUNT
> +#define CPUID_10_2_EDX_COS_MAX          MAX_L2_MASK_COUNT
> +#define CPUID_10_3_EDX_COS_MAX          MAX_MBA_THRTL_COUNT

Worth these defines?  Seems easier to just use the MAX_L3...
etc

> +
>  #define TYPE_RDT "rdt"
>  #define RDT_NUM_RMID_PROP "rmids"
>  
> @@ -57,6 +61,10 @@ struct RDTState {
>  
>  struct RDTStateClass { };
>  
> +uint32_t rdt_get_cpuid_10_1_edx_cos_max(void) { return CPUID_10_1_EDX_COS_MAX; }
> +uint32_t rdt_get_cpuid_10_2_edx_cos_max(void) { return CPUID_10_2_EDX_COS_MAX; }
> +uint32_t rdt_get_cpuid_10_3_edx_cos_max(void) { return CPUID_10_3_EDX_COS_MAX; }
> +
>  bool rdt_associate_rmid_cos(uint64_t msr_ia32_pqr_assoc) {
>      X86CPU *cpu = X86_CPU(current_cpu);
>      RDTStateInstance *rdt = cpu->rdt;
> diff --git a/include/hw/i386/rdt.h b/include/hw/i386/rdt.h
> index 8092c5f290..51d36822f0 100644
> --- a/include/hw/i386/rdt.h
> +++ b/include/hw/i386/rdt.h
> @@ -9,7 +9,12 @@ typedef struct RDTStateInstance RDTStateInstance;
>  typedef struct RDTMonitor RDTMonitor;
>  typedef struct RDTAllocation RDTAllocation;
>  
> -#endif
> +uint32_t rdt_get_cpuid_10_1_edx_cos_max(void);
> +
> +uint32_t rdt_get_cpuid_10_2_edx_cos_max(void);
> +
> +uint32_t rdt_get_cpuid_10_3_edx_cos_max(void);

No need for blank lines between these related function
definitions.

> +
>  bool rdt_associate_rmid_cos(uint64_t msr_ia32_pqr_assoc);
>  
>  void rdt_write_msr_l3_mask(uint32_t pos, uint32_t val);
> @@ -23,3 +28,4 @@ uint32_t rdt_read_mba_thrtl(uint32_t pos);
>  uint64_t rdt_read_event_count(RDTStateInstance *rdt, uint32_t rmid, uint32_t event_id);
>  uint32_t rdt_max_rmid(RDTStateInstance *rdt);
>  
> +#endif

Fix that in earlier patch not here.

> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index bd0bbb75f2..0b3aca2d02 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -574,6 +574,17 @@ typedef enum X86Seg {
>  #define MSR_IA32_VMX_TRUE_ENTRY_CTLS     0x00000490
>  #define MSR_IA32_VMX_VMFUNC             0x00000491
>  
> +#define MSR_IA32_QM_EVTSEL                  0x0c8d
> +#define MSR_IA32_QM_CTR                     0x0c8e
> +#define MSR_IA32_PQR_ASSOC                  0x0c8f
> +
> +#define MSR_IA32_L3_CBM_BASE                0x0c90
> +#define MSR_IA32_L3_MASKS_END               0x0d0f
> +#define MSR_IA32_L2_CBM_BASE                0x0d10
> +#define MSR_IA32_L2_CBM_END                 0x0d4f
> +#define MSR_IA32_L2_QOS_Ext_BW_Thrtl_BASE   0xd50
> +#define MSR_IA32_L2_QOS_Ext_BW_Thrtl_END    0xd80
> +
>  #define MSR_APIC_START                  0x00000800
>  #define MSR_APIC_END                    0x000008ff
>  
> @@ -1778,6 +1789,9 @@ typedef struct CPUArchState {
>      uint64_t msr_ia32_feature_control;
>      uint64_t msr_ia32_sgxlepubkeyhash[4];
>  
> +    uint64_t msr_ia32_qm_evtsel;
> +    uint64_t msr_ia32_pqr_assoc;
> +
>      uint64_t msr_fixed_ctr_ctrl;
>      uint64_t msr_global_ctrl;
>      uint64_t msr_global_status;
> diff --git a/target/i386/tcg/sysemu/misc_helper.c b/target/i386/tcg/sysemu/misc_helper.c
> index 094aa56a20..e48e6b0da1 100644
> --- a/target/i386/tcg/sysemu/misc_helper.c
> +++ b/target/i386/tcg/sysemu/misc_helper.c
> @@ -25,6 +25,7 @@
>  #include "exec/address-spaces.h"
>  #include "exec/exec-all.h"
>  #include "tcg/helper-tcg.h"
> +#include "hw/i386/rdt.h"
>  #include "hw/i386/apic.h"
>  
>  void helper_outb(CPUX86State *env, uint32_t port, uint32_t data)
> @@ -293,6 +294,44 @@ void helper_wrmsr(CPUX86State *env)
>          env->msr_bndcfgs = val;
>          cpu_sync_bndcs_hflags(env);
>          break;
> +    case MSR_IA32_QM_EVTSEL:
> +        env->msr_ia32_qm_evtsel = val;
> +        break;
> +    case MSR_IA32_PQR_ASSOC:
> +    {
> +        env->msr_ia32_pqr_assoc = val;
> +        bool res = rdt_associate_rmid_cos(val);
QEMU tends to use traditional C style, so declare
variables at start of scope then blank line.
However...

> +        if (!res)
> +            goto error;
           if (rdt_associate_rmid_cos(val)) {
               goto error;
           }
> +        break;
> +    }
Drop this scoping as bool will have gone away.

> +    case MSR_IA32_L3_CBM_BASE ... MSR_IA32_L3_MASKS_END:
> +    {
> +        uint32_t pos = (uint32_t)env->regs[R_ECX] - MSR_IA32_L3_CBM_BASE;
blank line

> +        if (pos >= rdt_get_cpuid_10_1_edx_cos_max()) {
> +            goto error;
> +        }
> +        rdt_write_msr_l3_mask(pos, val);
> +        break;
> +    }
> +    case MSR_IA32_L2_CBM_BASE ... MSR_IA32_L2_CBM_END:
> +    {
> +        uint32_t pos = (uint32_t)env->regs[R_ECX] - MSR_IA32_L2_CBM_BASE;
blank line.
> +        if (pos >= rdt_get_cpuid_10_2_edx_cos_max()) {
> +            goto error;
> +        }
> +        rdt_write_msr_l2_mask(pos, val);
> +        break;
> +    }
> +    case MSR_IA32_L2_QOS_Ext_BW_Thrtl_BASE ... MSR_IA32_L2_QOS_Ext_BW_Thrtl_END:
> +    {
> +        uint32_t pos = (uint32_t)env->regs[R_ECX] - MSR_IA32_L2_QOS_Ext_BW_Thrtl_BASE;

blank line

> +        if (pos >= rdt_get_cpuid_10_3_edx_cos_max()) {
> +            goto error;
> +        }
> +        rdt_write_mba_thrtl(pos, val);
> +        break;
> +    }
>      case MSR_APIC_START ... MSR_APIC_END: {
>          int ret;
>          int index = (uint32_t)env->regs[R_ECX] - MSR_APIC_START;
> @@ -472,6 +511,44 @@ void helper_rdmsr(CPUX86State *env)
>          val = (cs->nr_threads * cs->nr_cores) | (cs->nr_cores << 16);
>          break;
>      }
> +    case MSR_IA32_QM_CTR:
> +        val = rdt_read_event_count(x86_cpu->rdt,
> +                                   (env->msr_ia32_qm_evtsel >> 32) & 0xff,
> +                                   env->msr_ia32_qm_evtsel & 0xff);
> +        break;
> +    case MSR_IA32_QM_EVTSEL:
> +        val = env->msr_ia32_qm_evtsel;
> +        break;
> +    case MSR_IA32_PQR_ASSOC:
> +        val = env->msr_ia32_pqr_assoc;
> +        break;
> +    case MSR_IA32_L3_CBM_BASE ... MSR_IA32_L3_MASKS_END:
> +    {
> +        uint32_t pos = (uint32_t)env->regs[R_ECX] - MSR_IA32_L3_CBM_BASE;

blank line.

> +        if (pos >= rdt_get_cpuid_10_1_edx_cos_max()) {
> +            goto error;
> +        }
> +        val = rdt_read_l3_mask(pos);
> +        break;
> +    }
> +    case MSR_IA32_L2_CBM_BASE ... MSR_IA32_L2_CBM_END:
> +    {
> +        uint32_t pos = (uint32_t)env->regs[R_ECX] - MSR_IA32_L2_CBM_BASE;

blank line.

> +        if (pos >= rdt_get_cpuid_10_2_edx_cos_max()) {
> +            goto error;
> +        }
> +        val = rdt_read_l2_mask(pos);
> +        break;
> +    }
> +    case MSR_IA32_L2_QOS_Ext_BW_Thrtl_BASE ... MSR_IA32_L2_QOS_Ext_BW_Thrtl_END:
> +    {
> +        uint32_t pos = (uint32_t)env->regs[R_ECX] - MSR_IA32_L2_QOS_Ext_BW_Thrtl_BASE;

blank line.

> +        if (pos >= rdt_get_cpuid_10_3_edx_cos_max()) {
> +            goto error;
> +        }
> +        val = rdt_read_mba_thrtl(pos);
> +        break;
> +    }
>      case MSR_APIC_START ... MSR_APIC_END: {
>          int ret;
>          int index = (uint32_t)env->regs[R_ECX] - MSR_APIC_START;
> @@ -499,6 +576,9 @@ void helper_rdmsr(CPUX86State *env)
>      }
>      env->regs[R_EAX] = (uint32_t)(val);
>      env->regs[R_EDX] = (uint32_t)(val >> 32);
> +return;
    return;
fix the indent

blank line after the return.

> +error:
> +    raise_exception_err_ra(env, EXCP0D_GPF, 0, GETPC());
If this is only thing to do in error path it might be easier
to just do that inline instead of goto.

>  }
>  
>  void helper_flush_page(CPUX86State *env, target_ulong addr)