From: Andy Lutomirski <luto@kernel.org>
To: X86 ML <x86@kernel.org>
Cc: KVM list <kvm@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
xen-devel <Xen-devel@lists.xen.org>,
Andy Lutomirski <luto@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Arjan van de Ven <arjan@linux.intel.com>
Subject: [PATCH v3 3/5] x86/paravirt: Add paravirt_{read, write}_msr
Date: Fri, 11 Mar 2016 11:06:48 -0800 [thread overview]
Message-ID: <c7fb2aafd8a5885e9c333957abef9e29b691098e.1457723023.git.luto__10469.2920730033$1457723349$gmane$org@kernel.org> (raw)
In-Reply-To: <cover.1457723023.git.luto@kernel.org>
In-Reply-To: <cover.1457723023.git.luto@kernel.org>
This adds paravirt hooks 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 OOPS on #GP on Xen. I think that
should be done separately by the Xen maintainers.
Signed-off-by: Andy Lutomirski <luto@kernel.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 1487054a1a70..13da359881d7 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -119,8 +119,9 @@ 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 2e49228ed9a3..68297d87e85c 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -129,6 +129,17 @@ 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 5a06cccd36f0..b85aec45a1b8 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 8aad95478ae5..f9583917c7c4 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 ff2df20d0067..548cd3e02b9e 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,
--
2.5.0
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next prev parent reply other threads:[~2016-03-11 19:06 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1457723023.git.luto@kernel.org>
2016-03-11 19:06 ` [PATCH v3 1/5] x86/paravirt: Add _safe to the read_msr and write_msr PV hooks Andy Lutomirski
2016-03-11 19:06 ` [PATCH v3 2/5] x86/msr: Carry on after a non-"safe" MSR access fails without !panic_on_oops Andy Lutomirski
2016-03-11 19:06 ` Andy Lutomirski [this message]
2016-03-11 19:06 ` [PATCH v3 4/5] x86/paravirt: Make "unsafe" MSR accesses unsafe even if PARAVIRT=y Andy Lutomirski
2016-03-11 19:06 ` [PATCH v3 5/5] x86/msr: Set the return value to zero when native_rdmsr_safe fails Andy Lutomirski
[not found] ` <35f2f107e0d85473a0e66c08f93d571a9c72b7fc.1457723023.git.luto@kernel.org>
2016-03-12 15:31 ` [PATCH v3 2/5] x86/msr: Carry on after a non-"safe" MSR access fails without !panic_on_oops Ingo Molnar
2016-03-12 15:36 ` Ingo Molnar
[not found] ` <20160312153615.GB17873@gmail.com>
2016-03-12 17:32 ` Andy Lutomirski
[not found] ` <c7fb2aafd8a5885e9c333957abef9e29b691098e.1457723023.git.luto@kernel.org>
2016-03-14 14:02 ` [PATCH v3 3/5] x86/paravirt: Add paravirt_{read, write}_msr Paolo Bonzini
[not found] ` <56E6C492.5060308@redhat.com>
2016-03-14 16:53 ` Andy Lutomirski
2016-03-14 16:58 ` Linus Torvalds
2016-03-14 17:02 ` Andy Lutomirski
[not found] ` <CALCETrWYmJdOeHqjR6-Uyqiyym35DOjFpsB1xhgTHO_JB==EMA@mail.gmail.com>
2016-03-15 8:49 ` Paolo Bonzini
2016-03-15 8:56 ` Paolo Bonzini
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