linux-kernel - [PATCH v1 6/6] KVM: VMX: Get PT state from xsave area to variables

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Date:   Thu, 16 May 2019 16:25:14 +0800
From:   Luwei Kang <luwei.kang@...el.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        x86@...nel.org, pbonzini@...hat.com, rkrcmar@...hat.com,
        Luwei Kang <luwei.kang@...el.com>
Subject: [PATCH v1 6/6] KVM: VMX: Get PT state from xsave area to variables

This patch get the Intel PT state from xsave area to
variables when PT is change from enabled to disabled.
Because PT state is saved/restored to/from xsave area
by XSAVES/XRSTORES instructions when Intel PT is enabled.
The KVM guest may read this MSRs when PT is disabled
but the real value is saved in xsave area not variables.

Signed-off-by: Luwei Kang <luwei.kang@...el.com>
---
 arch/x86/kvm/vmx/vmx.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d323e6b..d3e2569 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1000,6 +1000,16 @@ static inline void pt_save_msr(struct pt_state *ctx, u32 addr_range)
 		rdmsrl(MSR_IA32_RTIT_ADDR0_A + i, ctx->rtit_addrx_ab[i]);
 }
 
+static void pt_state_get(struct pt_state *ctx, struct fpu *fpu, u32 addr_range)
+{
+	char *buff = fpu->state.xsave.extended_state_area;
+
+	/* skip riti_ctl register */
+	memcpy(&ctx->rtit_output_base, buff + sizeof(u64),
+			sizeof(struct pt_state) - sizeof(u64) +
+			sizeof(u64) * addr_range * 2);
+}
+
 static void pt_guest_enter(struct vcpu_vmx *vmx)
 {
 	struct pt_desc *desc;
@@ -1040,6 +1050,9 @@ static void pt_guest_enter(struct vcpu_vmx *vmx)
 			pt_save_msr(desc->host_ctx, desc->addr_range);
 			pt_load_msr(desc->guest_ctx, desc->addr_range);
 		}
+	} else if (desc->pt_xsave && desc->guest_xs->initialized) {
+		pt_state_get(desc->guest_ctx, desc->guest_xs, desc->addr_range);
+		desc->guest_xs->initialized = 0;
 	}
 }
 
-- 
1.8.3.1