linux-kernel - [PATCH 3.2 196/199] Revert "KVM: x86: expose MSR_TSC

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Message-ID: <lsq.1489146370.91172867@decadent.org.uk>
Date:   Fri, 10 Mar 2017 11:46:10 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Eric Wheeler" <kvm@...ts.ewheeler.net>
Subject: [PATCH 3.2 196/199] Revert "KVM: x86: expose MSR_TSC_AUX to
 userspace"

3.2.87-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ben Hutchings <ben@...adent.org.uk>

This reverts commit bc48f6f5a8c6d628a1af649306eaf906493bb986, which was
commit 9dbe6cf941a6fe82933aef565e4095fb10f65023 upstream.  It depends on
several other large commits to work, and without them causes a regression.

References: https://bugzilla.redhat.com/show_bug.cgi?id=1408333
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Cc: Eric Wheeler <kvm@...ts.ewheeler.net>
---
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -843,8 +843,7 @@ static u32 msrs_to_save[] = {
 #ifdef CONFIG_X86_64
 	MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR,
 #endif
-	MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA,
-	MSR_TSC_AUX,
+	MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA
 };
 
 static unsigned num_msrs_to_save;
@@ -3882,20 +3881,6 @@ static void kvm_init_msr_list(void)
 	for (i = j = KVM_SAVE_MSRS_BEGIN; i < ARRAY_SIZE(msrs_to_save); i++) {
 		if (rdmsr_safe(msrs_to_save[i], &dummy[0], &dummy[1]) < 0)
 			continue;
-
-		/*
-		 * Even MSRs that are valid in the host may not be exposed
-		 * to the guests in some cases.
-		 */
-		switch (msrs_to_save[i]) {
-		case MSR_TSC_AUX:
-			if (!kvm_x86_ops->rdtscp_supported())
-				continue;
-			break;
-		default:
-			break;
-		}
-
 		if (j < i)
 			msrs_to_save[j] = msrs_to_save[i];
 		j++;