Re: [PATCH v5 2/9] vmx: spp: Add control flags for Sub-Page Protection(SPP)

From: Jim Mattson
Date: Fri Oct 04 2019 - 16:48:49 EST

On Tue, Sep 17, 2019 at 1:52 AM Yang Weijiang <weijiang.yang@xxxxxxxxx> wrote:
>
> Check SPP capability in MSR_IA32_VMX_PROCBASED_CTLS2, its 23-bit
> indicates SPP capability. Enable SPP feature bit in CPU capabilities
> bitmap if it's supported.
>
> Co-developed-by: He Chen <he.chen@xxxxxxxxxxxxxxx>
> Signed-off-by: He Chen <he.chen@xxxxxxxxxxxxxxx>
> Co-developed-by: Zhang Yi <yi.z.zhang@xxxxxxxxxxxxxxx>
> Signed-off-by: Zhang Yi <yi.z.zhang@xxxxxxxxxxxxxxx>
> Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
> ---
> arch/x86/include/asm/cpufeatures.h | 1 +
> arch/x86/include/asm/vmx.h | 1 +
> arch/x86/kernel/cpu/intel.c | 4 ++++
> arch/x86/kvm/mmu.h | 2 ++
> arch/x86/kvm/vmx/capabilities.h | 5 +++++
> arch/x86/kvm/vmx/vmx.c | 10 ++++++++++
> 6 files changed, 23 insertions(+)
>
> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> index e880f2408e29..ee2c76fdadf6 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -228,6 +228,7 @@
> #define X86_FEATURE_FLEXPRIORITY ( 8*32+ 2) /* Intel FlexPriority */
> #define X86_FEATURE_EPT ( 8*32+ 3) /* Intel Extended Page Table */
> #define X86_FEATURE_VPID ( 8*32+ 4) /* Intel Virtual Processor ID */
> +#define X86_FEATURE_SPP ( 8*32+ 5) /* Intel EPT-based Sub-Page Write Protection */
>
> #define X86_FEATURE_VMMCALL ( 8*32+15) /* Prefer VMMCALL to VMCALL */
> #define X86_FEATURE_XENPV ( 8*32+16) /* "" Xen paravirtual guest */
> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> index a39136b0d509..e1137807affc 100644
> --- a/arch/x86/include/asm/vmx.h
> +++ b/arch/x86/include/asm/vmx.h
> @@ -68,6 +68,7 @@
> #define SECONDARY_EXEC_XSAVES 0x00100000
> #define SECONDARY_EXEC_PT_USE_GPA 0x01000000
> #define SECONDARY_EXEC_MODE_BASED_EPT_EXEC 0x00400000
> +#define SECONDARY_EXEC_ENABLE_SPP 0x00800000
> #define SECONDARY_EXEC_TSC_SCALING 0x02000000
>
> #define PIN_BASED_EXT_INTR_MASK 0x00000001
> diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
> index 8d6d92ebeb54..27617e522f01 100644
> --- a/arch/x86/kernel/cpu/intel.c
> +++ b/arch/x86/kernel/cpu/intel.c
> @@ -503,6 +503,7 @@ static void detect_vmx_virtcap(struct cpuinfo_x86 *c)
> #define X86_VMX_FEATURE_PROC_CTLS2_EPT 0x00000002
> #define X86_VMX_FEATURE_PROC_CTLS2_VPID 0x00000020
> #define x86_VMX_FEATURE_EPT_CAP_AD 0x00200000
> +#define X86_VMX_FEATURE_PROC_CTLS2_SPP 0x00800000
>
> u32 vmx_msr_low, vmx_msr_high, msr_ctl, msr_ctl2;
> u32 msr_vpid_cap, msr_ept_cap;
> @@ -513,6 +514,7 @@ static void detect_vmx_virtcap(struct cpuinfo_x86 *c)
> clear_cpu_cap(c, X86_FEATURE_EPT);
> clear_cpu_cap(c, X86_FEATURE_VPID);
> clear_cpu_cap(c, X86_FEATURE_EPT_AD);
> + clear_cpu_cap(c, X86_FEATURE_SPP);
>
> rdmsr(MSR_IA32_VMX_PROCBASED_CTLS, vmx_msr_low, vmx_msr_high);
> msr_ctl = vmx_msr_high | vmx_msr_low;
> @@ -536,6 +538,8 @@ static void detect_vmx_virtcap(struct cpuinfo_x86 *c)
> }
> if (msr_ctl2 & X86_VMX_FEATURE_PROC_CTLS2_VPID)
> set_cpu_cap(c, X86_FEATURE_VPID);
> + if (msr_ctl2 & X86_VMX_FEATURE_PROC_CTLS2_SPP)
> + set_cpu_cap(c, X86_FEATURE_SPP);

SPP requires EPT, so this could be moved up next to the EPT_AD check.
In fact, I would suggest changing 'SPP' to 'EPT_SPP' to make it clear
that this feature is *EPT* sub-page permissions.

> }
> }
>
> diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
> index 54c2a377795b..3c1423526a98 100644
> --- a/arch/x86/kvm/mmu.h
> +++ b/arch/x86/kvm/mmu.h
> @@ -26,6 +26,8 @@
> #define PT_PAGE_SIZE_MASK (1ULL << PT_PAGE_SIZE_SHIFT)
> #define PT_PAT_MASK (1ULL << 7)
> #define PT_GLOBAL_MASK (1ULL << 8)
> +#define PT_SPP_SHIFT 61
> +#define PT_SPP_MASK (1ULL << PT_SPP_SHIFT)

Since these constants are only applicable to EPT, would it be more
appropriate to define them in paging_tmpl.h, under '#elif PTTYPE ==
PTTYPE_EPT'? If not, it seems that they should at least be renamed to
PT64_SPP_* for consistency with the other macros here.

> #define PT64_NX_SHIFT 63
> #define PT64_NX_MASK (1ULL << PT64_NX_SHIFT)
>
> diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
> index d6664ee3d127..e3bde7a32123 100644
> --- a/arch/x86/kvm/vmx/capabilities.h
> +++ b/arch/x86/kvm/vmx/capabilities.h
> @@ -241,6 +241,11 @@ static inline bool cpu_has_vmx_pml(void)
> return vmcs_config.cpu_based_2nd_exec_ctrl & SECONDARY_EXEC_ENABLE_PML;
> }
>
> +static inline bool cpu_has_vmx_ept_spp(void)
> +{
> + return vmcs_config.cpu_based_2nd_exec_ctrl & SECONDARY_EXEC_ENABLE_SPP;
> +}
> +
> static inline bool vmx_xsaves_supported(void)
> {
> return vmcs_config.cpu_based_2nd_exec_ctrl &
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index c030c96fc81a..8ecf9cb24879 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -60,6 +60,7 @@
> #include "vmcs12.h"
> #include "vmx.h"
> #include "x86.h"
> +#include "spp.h"
>
> MODULE_AUTHOR("Qumranet");
> MODULE_LICENSE("GPL");
> @@ -113,6 +114,7 @@ module_param_named(pml, enable_pml, bool, S_IRUGO);
>
> static bool __read_mostly dump_invalid_vmcs = 0;
> module_param(dump_invalid_vmcs, bool, 0644);
> +static bool __read_mostly spp_supported = 0;
>
> #define MSR_BITMAP_MODE_X2APIC 1
> #define MSR_BITMAP_MODE_X2APIC_APICV 2
> @@ -2279,6 +2281,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
> SECONDARY_EXEC_RDSEED_EXITING |
> SECONDARY_EXEC_RDRAND_EXITING |
> SECONDARY_EXEC_ENABLE_PML |
> + SECONDARY_EXEC_ENABLE_SPP |
> SECONDARY_EXEC_TSC_SCALING |
> SECONDARY_EXEC_PT_USE_GPA |
> SECONDARY_EXEC_PT_CONCEAL_VMX |
> @@ -3931,6 +3934,9 @@ static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx)
> if (!enable_pml)
> exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
>
> + if (!spp_supported)
> + exec_control &= ~SECONDARY_EXEC_ENABLE_SPP;
> +
> if (vmx_xsaves_supported()) {
> /* Exposing XSAVES only when XSAVE is exposed */
> bool xsaves_enabled =
> @@ -7521,6 +7527,10 @@ static __init int hardware_setup(void)
> if (!cpu_has_vmx_flexpriority())
> flexpriority_enabled = 0;
>
> + if (cpu_has_vmx_ept_spp() && enable_ept &&
> + boot_cpu_has(X86_FEATURE_SPP))
> + spp_supported = 1;

Don't cpu_has_vmx_ept_spp() and boot_cpu_has(X86_FEATURE_SPP) test
exactly the same thing?

> if (!cpu_has_virtual_nmis())
> enable_vnmi = 0;
>
> --
> 2.17.2
>