On 06/14/2012 05:04 AM, Mao, Junjie wrote:
> This patch handles PCID/INVPCID for guests.
>
> Process-context identifiers (PCIDs) are a facility by which a logical processor
> may cache information for multiple linear-address spaces so that the processor
> may retain cached information when software switches to a different linear
> address space. Refer to section 4.10.1 in IA32 Intel Software Developer's Manual
> Volume 3A for details.
>
> For guests with EPT, the PCID feature is enabled and INVPCID behaves as running
> natively.
> For guests without EPT, the PCID feature is disabled and INVPCID triggers #UD.
>
>
> #endif
> unsigned f_rdtscp = kvm_x86_ops->rdtscp_supported() ? F(RDTSCP) : 0;
> + unsigned f_pcid = boot_cpu_has(X86_FEATURE_PCID) ? F(PCID) : 0;
Unneeded, just put F(PCID) below.
> + unsigned f_invpcid = kvm_x86_ops->invpcid_supported() ? F(INVPCID) : 0;
>
> /* cpuid 1.edx */
> const u32 kvm_supported_word0_x86_features =
> @@ -228,7 +230,7 @@ static int do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
> 0 /* DS-CPL, VMX, SMX, EST */ |
> 0 /* TM2 */ | F(SSSE3) | 0 /* CNXT-ID */ | 0 /* Reserved */ |
> F(FMA) | F(CX16) | 0 /* xTPR Update, PDCM */ |
> - 0 /* Reserved, DCA */ | F(XMM4_1) |
> + f_pcid | 0 /* Reserved, DCA */ | F(XMM4_1) |
> @@ -1739,6 +1745,11 @@ static bool vmx_rdtscp_supported(void)
> return cpu_has_vmx_rdtscp();
> }
>
> +static bool vmx_invpcid_supported(void)
> +{
> + return cpu_has_vmx_invpcid();
Should that have && ept_enabled? You turn off invpcid below if
!ept_enabled.
> +}
> +
> /*
> * Swap MSR entry in host/guest MSR entry array.
> */
> @@ -2458,7 +2469,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
> SECONDARY_EXEC_ENABLE_EPT |
> SECONDARY_EXEC_UNRESTRICTED_GUEST |
> SECONDARY_EXEC_PAUSE_LOOP_EXITING |
> - SECONDARY_EXEC_RDTSCP;
> + SECONDARY_EXEC_RDTSCP |
> + SECONDARY_EXEC_ENABLE_INVPCID;
> if (adjust_vmx_controls(min2, opt2,
> MSR_IA32_VMX_PROCBASED_CTLS2,
> &_cpu_based_2nd_exec_control) < 0)
> @@ -3731,6 +3743,8 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
> if (!enable_ept) {
> exec_control &= ~SECONDARY_EXEC_ENABLE_EPT;
> enable_unrestricted_guest = 0;
> + /* Enable INVPCID for non-ept guests may cause performance regression. */
> + exec_control &= ~SECONDARY_EXEC_ENABLE_INVPCID;
> }
> if (!enable_unrestricted_guest)
> exec_control &= ~SECONDARY_EXEC_UNRESTRICTED_GUEST;
This code is unneeded..
> @@ -6467,6 +6481,23 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
> }
> }
> }
> +
> + if (vmx_invpcid_supported()) {
> + exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
> + /* Exposing INVPCID only when PCID is exposed */
> + best = kvm_find_cpuid_entry(vcpu, 0x7, 0);
> + if (best && (best->ecx & bit(X86_FEATURE_INVPCID)) && guest_cpuid_has_pcid(vcpu)) {
> + exec_control |= SECONDARY_EXEC_ENABLE_INVPCID;
> + vmcs_write32(SECONDARY_VM_EXEC_CONTROL,
> + exec_control);
> + } else {
> + exec_control &= ~SECONDARY_EXEC_ENABLE_INVPCID;
> + vmcs_write32(SECONDARY_VM_EXEC_CONTROL,
> + exec_control);
> + if (best)
> + best->ecx &= ~bit(X86_FEATURE_INVPCID);
> + }
> + }
> }
Since you override it here anyway. But maybe it's needed if the host
never calls KVM_SET_CPUID.
>
> static void vmx_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
> @@ -6610,6 +6641,9 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> page_to_phys(vmx->nested.apic_access_page));
> }
>
> + /* Explicitly disable INVPCID until PCID for L2 guest is supported */
> + exec_control &= ~SECONDARY_EXEC_ENABLE_INVPCID;
> +
We can't just disable it without the guest knowing. If we don't expose
INCPCID through the MSR, then we should fail VMKLAUNCH or VMRESUME is
this bit is set.
> vmcs_write32(SECONDARY_VM_EXEC_CONTROL, exec_control);
> }
>
> @@ -528,6 +528,10 @@ int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
> return 1;
> }
>
> + if ((old_cr0 & X86_CR0_PG) && !(cr0 & X86_CR0_PG) &&
> + kvm_read_cr4_bits(vcpu, X86_CR4_PCIDE))
> + return 1;
Why check old_cr0?
>
> + if ((cr4 & X86_CR4_PCIDE) && !(old_cr4 & X86_CR4_PCIDE)) {
> + if (!guest_cpuid_has_pcid(vcpu))
> + return 1;
> +
> + /* PCID can not be enabled when cr3[11:0]!=000H or EFER.LMA=0 */
> + if ((kvm_read_cr3(vcpu) & X86_CR3_PCID_MASK) || !is_long_mode(vcpu))
> + return 1;
> + }
> +
> if (kvm_x86_ops->set_cr4(vcpu, cr4))
> return 1;
>
> - if ((cr4 ^ old_cr4) & pdptr_bits)
> + if (((cr4 ^ old_cr4) & pdptr_bits) ||
> + (!(cr4 & X86_CR4_PCIDE) && (old_cr4 & X86_CR4_PCIDE)))
> kvm_mmu_reset_context(vcpu);
You can do
if ((cr4 ^ old_cr4) & (pdptr_bits | X86_CR4_PCIDE))
...
> @@ -626,8 +640,12 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
> }
>
> if (is_long_mode(vcpu)) {
> - if (cr3 & CR3_L_MODE_RESERVED_BITS)
> - return 1;
> + if (kvm_read_cr4(vcpu) & X86_CR4_PCIDE) {
> + if (cr3 & CR3_PCID_ENABLED_RESERVED_BITS)
> + return 1;
> + } else
> + if (cr3 & CR3_L_MODE_RESERVED_BITS)
> + return 1;
> } else {
> if (is_pae(vcpu)) {
> if (cr3 & CR3_PAE_RESERVED_BITS)
I'm worried about the order of writes in
kvm_arch_vcpu_ioctl_set_sregs(). We might end up in a situation where
we we can't load all registers due to all those checks.
--
error compiling committee.c: too many arguments to function
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