[PATCH v7 09/13] KVM: x86: Implement Intel Processor Trace context switch

Luwei Kang
2018-05-03T12:13:24Z

From: Chao Peng <chao.p.peng@linux.intel.com>

Load/Store Intel processor trace register in context switch.
MSR IA32_RTIT_CTL is loaded/stored automatically from VMCS.
In HOST mode, we just need to restore the status of IA32_RTIT_CTL.
In HOST_GUEST mode, we need load/resore PT MSRs only when PT is
enabled in guest.

Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Signed-off-by: Luwei Kang <luwei.kang@intel.com>
---
arch/x86/kvm/vmx.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 60 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 9a5c26d..a08c61b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2385,6 +2385,55 @@ static unsigned long segment_base(u16 selector)
}
#endif

+static inline void pt_load_msr(struct pt_ctx *ctx, u32 range_cnt)
+{
+ u32 i;
+
+ wrmsrl(MSR_IA32_RTIT_STATUS, ctx->status);
+ wrmsrl(MSR_IA32_RTIT_OUTPUT_BASE, ctx->output_base);
+ wrmsrl(MSR_IA32_RTIT_OUTPUT_MASK, ctx->output_mask);
+ wrmsrl(MSR_IA32_RTIT_CR3_MATCH, ctx->cr3_match);
+ for (i = 0; i < range_cnt; i++)
+ wrmsrl(MSR_IA32_RTIT_ADDR0_A + i, ctx->addrs[i]);
+}
+
+static inline void pt_save_msr(struct pt_ctx *ctx, u32 range_cnt)
+{
+ u32 i;
+
+ rdmsrl(MSR_IA32_RTIT_STATUS, ctx->status);
+ rdmsrl(MSR_IA32_RTIT_OUTPUT_BASE, ctx->output_base);
+ rdmsrl(MSR_IA32_RTIT_OUTPUT_MASK, ctx->output_mask);
+ rdmsrl(MSR_IA32_RTIT_CR3_MATCH, ctx->cr3_match);
+ for (i = 0; i < range_cnt; i++)
+ rdmsrl(MSR_IA32_RTIT_ADDR0_A + i, ctx->addrs[i]);
+}
+
+static void pt_guest_enter(struct vcpu_vmx *vmx)
+{
+ if (pt_mode == PT_MODE_HOST || pt_mode == PT_MODE_HOST_GUEST)
+ rdmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl);
+
+ if (pt_mode == PT_MODE_HOST_GUEST &&
+ vmx->pt_desc.guest.ctl & RTIT_CTL_TRACEEN) {
+ wrmsrl(MSR_IA32_RTIT_CTL, 0);
+ pt_save_msr(&vmx->pt_desc.host, vmx->pt_desc.range_cnt);
+ pt_load_msr(&vmx->pt_desc.guest, vmx->pt_desc.range_cnt);
+ }
+}
+
+static void pt_guest_exit(struct vcpu_vmx *vmx)
+{
+ if (pt_mode == PT_MODE_HOST_GUEST &&
+ vmx->pt_desc.guest.ctl & RTIT_CTL_TRACEEN) {
+ pt_save_msr(&vmx->pt_desc.guest, vmx->pt_desc.range_cnt);
+ pt_load_msr(&vmx->pt_desc.host, vmx->pt_desc.range_cnt);
+ }
+
+ if (pt_mode == PT_MODE_HOST || pt_mode == PT_MODE_HOST_GUEST)
+ wrmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl);
+}
+
static void vmx_save_host_state(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -6119,6 +6168,13 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx)
vmcs_write64(PML_ADDRESS, page_to_phys(vmx->pml_pg));
vmcs_write16(GUEST_PML_INDEX, PML_ENTITY_NUM - 1);
}
+
+ if (pt_mode == PT_MODE_HOST_GUEST) {
+ memset(&vmx->pt_desc, 0, sizeof(vmx->pt_desc));
+ /* Bit[6~0] are forced to 1, writes are ignored. */
+ vmx->pt_desc.guest.output_mask = 0x7F;
+ vmcs_write64(GUEST_IA32_RTIT_CTL, 0);
+ }
}

static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
@@ -9794,6 +9850,8 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
vcpu->arch.pkru != vmx->host_pkru)
__write_pkru(vcpu->arch.pkru);

+ pt_guest_enter(vmx);
+
atomic_switch_perf_msrs(vmx);

vmx_arm_hv_timer(vcpu);
@@ -9988,6 +10046,8 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
| (1 << VCPU_EXREG_CR3));
vcpu->arch.regs_dirty = 0;

+ pt_guest_exit(vmx);
+
/*
* eager fpu is enabled if PKEY is supported and CR4 is switched
* back on host, so it is safe to read guest PKRU from current
--
1.8.3.1