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Date: Wed, 13 Apr 2016 04:45:41 -0700
From: tip-bot for Andy Lutomirski <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
bp@...en8.de, pbonzini@...hat.com, arjan@...ux.intel.com,
luto@...nel.org, Xen-devel@...ts.xen.org, hpa@...or.com,
peterz@...radead.org, kvm@...r.kernel.org, mingo@...nel.org,
boris.ostrovsky@...cle.com, tglx@...utronix.de,
linux-kernel@...r.kernel.org
Subject: [tip:x86/asm] x86/paravirt: Add paravirt_{read,write}_msr()
Commit-ID: dd2f4a004b016bbfb64f1de49cb45e66232e40a6
Gitweb: http://git.kernel.org/tip/dd2f4a004b016bbfb64f1de49cb45e66232e40a6
Author: Andy Lutomirski <luto@...nel.org>
AuthorDate: Sat, 2 Apr 2016 07:01:38 -0700
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 13 Apr 2016 11:37:46 +0200
x86/paravirt: Add paravirt_{read,write}_msr()
This adds paravirt callbacks for unsafe MSR access. On native, they
call native_{read,write}_msr(). On Xen, they use xen_{read,write}_msr_safe().
Nothing uses them yet for ease of bisection. The next patch will
use them in rdmsrl(), wrmsrl(), etc.
I intentionally didn't make them warn on #GP on Xen. I think that
should be done separately by the Xen maintainers.
Tested-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: Andy Lutomirski <luto@...nel.org>
Acked-by: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Arjan van de Ven <arjan@...ux.intel.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: KVM list <kvm@...r.kernel.org>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: xen-devel <Xen-devel@...ts.xen.org>
Link: http://lkml.kernel.org/r/880eebc5dcd2ad9f310d41345f82061ea500e9fa.1459605520.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
arch/x86/include/asm/msr.h | 5 +++--
arch/x86/include/asm/paravirt.h | 11 +++++++++++
arch/x86/include/asm/paravirt_types.h | 10 ++++++++--
arch/x86/kernel/paravirt.c | 2 ++
arch/x86/xen/enlighten.c | 23 +++++++++++++++++++++++
5 files changed, 47 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index 25f169c..00050c0 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -111,8 +111,9 @@ static inline unsigned long long native_read_msr_safe(unsigned int msr,
return EAX_EDX_VAL(val, low, high);
}
-static inline void native_write_msr(unsigned int msr,
- unsigned low, unsigned high)
+/* Can be uninlined because referenced by paravirt */
+notrace static inline void native_write_msr(unsigned int msr,
+ unsigned low, unsigned high)
{
asm volatile("1: wrmsr\n"
"2:\n"
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 81ef2d5..97839fa 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -130,6 +130,17 @@ static inline void wbinvd(void)
#define get_kernel_rpl() (pv_info.kernel_rpl)
+static inline u64 paravirt_read_msr(unsigned msr)
+{
+ return PVOP_CALL1(u64, pv_cpu_ops.read_msr, msr);
+}
+
+static inline void paravirt_write_msr(unsigned msr,
+ unsigned low, unsigned high)
+{
+ return PVOP_VCALL3(pv_cpu_ops.write_msr, msr, low, high);
+}
+
static inline u64 paravirt_read_msr_safe(unsigned msr, int *err)
{
return PVOP_CALL2(u64, pv_cpu_ops.read_msr_safe, msr, err);
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 09c9e1d..b4a23ea 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -155,8 +155,14 @@ struct pv_cpu_ops {
void (*cpuid)(unsigned int *eax, unsigned int *ebx,
unsigned int *ecx, unsigned int *edx);
- /* MSR operations.
- err = 0/-EIO. wrmsr returns 0/-EIO. */
+ /* Unsafe MSR operations. These will warn or panic on failure. */
+ u64 (*read_msr)(unsigned int msr);
+ void (*write_msr)(unsigned int msr, unsigned low, unsigned high);
+
+ /*
+ * Safe MSR operations.
+ * read sets err to 0 or -EIO. write returns 0 or -EIO.
+ */
u64 (*read_msr_safe)(unsigned int msr, int *err);
int (*write_msr_safe)(unsigned int msr, unsigned low, unsigned high);
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 8aad954..f958391 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -339,6 +339,8 @@ __visible struct pv_cpu_ops pv_cpu_ops = {
.write_cr8 = native_write_cr8,
#endif
.wbinvd = native_wbinvd,
+ .read_msr = native_read_msr,
+ .write_msr = native_write_msr,
.read_msr_safe = native_read_msr_safe,
.write_msr_safe = native_write_msr_safe,
.read_pmc = native_read_pmc,
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 13f756f..6ab6722 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1092,6 +1092,26 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
return ret;
}
+static u64 xen_read_msr(unsigned int msr)
+{
+ /*
+ * This will silently swallow a #GP from RDMSR. It may be worth
+ * changing that.
+ */
+ int err;
+
+ return xen_read_msr_safe(msr, &err);
+}
+
+static void xen_write_msr(unsigned int msr, unsigned low, unsigned high)
+{
+ /*
+ * This will silently swallow a #GP from WRMSR. It may be worth
+ * changing that.
+ */
+ xen_write_msr_safe(msr, low, high);
+}
+
void xen_setup_shared_info(void)
{
if (!xen_feature(XENFEAT_auto_translated_physmap)) {
@@ -1222,6 +1242,9 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = {
.wbinvd = native_wbinvd,
+ .read_msr = xen_read_msr,
+ .write_msr = xen_write_msr,
+
.read_msr_safe = xen_read_msr_safe,
.write_msr_safe = xen_write_msr_safe,
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