* [PATCH RFC 1/4] x86: introduce cpu_has_invpcid
2018-02-15 12:10 [PATCH RFC 0/4] Use INVPCID to flush global mappings Wei Liu
@ 2018-02-15 12:10 ` Wei Liu
2018-02-15 12:31 ` Jan Beulich
2018-02-15 12:10 ` [PATCH RFC 2/4] x86: report if PCID and INVPCID are supported Wei Liu
` (3 subsequent siblings)
4 siblings, 1 reply; 13+ messages in thread
From: Wei Liu @ 2018-02-15 12:10 UTC (permalink / raw)
To: Xen-devel; +Cc: Juergen Gross, Andrew Cooper, Wei Liu, Jan Beulich
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
xen/include/asm-x86/cpufeature.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/xen/include/asm-x86/cpufeature.h b/xen/include/asm-x86/cpufeature.h
index 55b696ed07..db8072279d 100644
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -93,6 +93,7 @@
#define cpu_has_avx2 boot_cpu_has(X86_FEATURE_AVX2)
#define cpu_has_smep boot_cpu_has(X86_FEATURE_SMEP)
#define cpu_has_bmi2 boot_cpu_has(X86_FEATURE_BMI2)
+#define cpu_has_invpcid boot_cpu_has(X86_FEATURE_INVPCID)
#define cpu_has_rtm boot_cpu_has(X86_FEATURE_RTM)
#define cpu_has_fpu_sel (!boot_cpu_has(X86_FEATURE_NO_FPU_SEL))
#define cpu_has_mpx boot_cpu_has(X86_FEATURE_MPX)
--
2.11.0
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply related [flat|nested] 13+ messages in thread* Re: [PATCH RFC 1/4] x86: introduce cpu_has_invpcid
2018-02-15 12:10 ` [PATCH RFC 1/4] x86: introduce cpu_has_invpcid Wei Liu
@ 2018-02-15 12:31 ` Jan Beulich
0 siblings, 0 replies; 13+ messages in thread
From: Jan Beulich @ 2018-02-15 12:31 UTC (permalink / raw)
To: Wei Liu; +Cc: Juergen Gross, Andrew Cooper, Xen-devel
>>> On 15.02.18 at 13:10, <wei.liu2@citrix.com> wrote:
> --- a/xen/include/asm-x86/cpufeature.h
> +++ b/xen/include/asm-x86/cpufeature.h
> @@ -93,6 +93,7 @@
> #define cpu_has_avx2 boot_cpu_has(X86_FEATURE_AVX2)
> #define cpu_has_smep boot_cpu_has(X86_FEATURE_SMEP)
> #define cpu_has_bmi2 boot_cpu_has(X86_FEATURE_BMI2)
> +#define cpu_has_invpcid boot_cpu_has(X86_FEATURE_INVPCID)
> #define cpu_has_rtm boot_cpu_has(X86_FEATURE_RTM)
> #define cpu_has_fpu_sel (!boot_cpu_has(X86_FEATURE_NO_FPU_SEL))
> #define cpu_has_mpx boot_cpu_has(X86_FEATURE_MPX)
Please fold into whatever patch is first using the new macro.
Jan
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH RFC 2/4] x86: report if PCID and INVPCID are supported
2018-02-15 12:10 [PATCH RFC 0/4] Use INVPCID to flush global mappings Wei Liu
2018-02-15 12:10 ` [PATCH RFC 1/4] x86: introduce cpu_has_invpcid Wei Liu
@ 2018-02-15 12:10 ` Wei Liu
2018-02-15 12:10 ` [PATCH RFC 3/4] x86: add invpcid.h Wei Liu
` (2 subsequent siblings)
4 siblings, 0 replies; 13+ messages in thread
From: Wei Liu @ 2018-02-15 12:10 UTC (permalink / raw)
To: Xen-devel; +Cc: Juergen Gross, Andrew Cooper, Wei Liu, Jan Beulich
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
xen/arch/x86/setup.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index ac530ece2c..89e42865a4 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1701,6 +1701,13 @@ void __init noreturn __start_xen(unsigned long mbi_p)
cpu_has_nx ? XENLOG_INFO : XENLOG_WARNING "Warning: ",
cpu_has_nx ? "" : "not ");
+
+ printk(XENLOG_INFO
+ "PCID (Process-Context IDentifier) %ssupported\n",
+ cpu_has_pcid ? "" : "not ");
+
+ printk(XENLOG_INFO "INVPCID %ssupported\n", cpu_has_invpcid ? "" : "not ");
+
/*
* We're going to setup domain0 using the module(s) that we stashed safely
* above our heap. The second module, if present, is an initrd ramdisk.
--
2.11.0
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCH RFC 3/4] x86: add invpcid.h
2018-02-15 12:10 [PATCH RFC 0/4] Use INVPCID to flush global mappings Wei Liu
2018-02-15 12:10 ` [PATCH RFC 1/4] x86: introduce cpu_has_invpcid Wei Liu
2018-02-15 12:10 ` [PATCH RFC 2/4] x86: report if PCID and INVPCID are supported Wei Liu
@ 2018-02-15 12:10 ` Wei Liu
2018-02-15 12:15 ` Andrew Cooper
2018-02-15 12:34 ` Jan Beulich
2018-02-15 12:10 ` [PATCH RFC 4/4] x86: use invpcid to do global flush Wei Liu
2018-02-15 15:38 ` [PATCH RFC 0/4] Use INVPCID to flush global mappings Juergen Gross
4 siblings, 2 replies; 13+ messages in thread
From: Wei Liu @ 2018-02-15 12:10 UTC (permalink / raw)
To: Xen-devel; +Cc: Juergen Gross, Andrew Cooper, Wei Liu, Jan Beulich
Provide the functions needed for different modes.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
xen/include/asm-x86/invpcid.h | 61 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 61 insertions(+)
create mode 100644 xen/include/asm-x86/invpcid.h
diff --git a/xen/include/asm-x86/invpcid.h b/xen/include/asm-x86/invpcid.h
new file mode 100644
index 0000000000..7c307ecfc3
--- /dev/null
+++ b/xen/include/asm-x86/invpcid.h
@@ -0,0 +1,61 @@
+#ifndef _ASM_X86_INVPCID_H_
+#define _ASM_X86_INVPCID_H_
+
+#include <xen/types.h>
+
+#define INVPCID_TYPE_INDIV_ADDR 0
+#define INVPCID_TYPE_SINGLE_CTXT 1
+#define INVPCID_TYPE_ALL_INCL_GLOBAL 2
+#define INVPCID_TYPE_ALL_NON_GLOBAL 3
+
+struct invpcid_desc {
+ uint64_t pcid:12;
+ uint64_t reserved:52;
+ uint64_t addr;
+};
+
+static inline void invpcid(unsigned long pcid, unsigned long addr,
+ unsigned long type)
+{
+ struct invpcid_desc desc = { .pcid = pcid, .addr = addr };
+
+ asm volatile ("invpcid (%0), %1"
+ : : "r" (&desc), "r" (type) : "memory" );
+}
+
+/* Flush all mappings for a given PCID and addr, not including globals */
+static inline void invpcid_flush_one(unsigned long pcid,
+ unsigned long addr)
+{
+ invpcid(pcid, addr, INVPCID_TYPE_INDIV_ADDR);
+}
+
+/* Flush all mappings for a given PCID, not including globals */
+static inline void invpcid_flush_single_context(unsigned long pcid)
+{
+ invpcid(pcid, 0, INVPCID_TYPE_SINGLE_CTXT);
+}
+
+/* Flush all mappings, including globals, for all PCIDs */
+static inline void invpcid_flush_all(void)
+{
+ invpcid(0, 0, INVPCID_TYPE_ALL_INCL_GLOBAL);
+}
+
+/* Flush all mappings for all PCIDs, excluding globals */
+static inline void invpcid_flush_all_nonglobals(void)
+{
+ invpcid(0, 0, INVPCID_TYPE_ALL_NON_GLOBAL);
+}
+
+#endif /* _ASM_X86_INVPCID_H_ */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
--
2.11.0
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply related [flat|nested] 13+ messages in thread* Re: [PATCH RFC 3/4] x86: add invpcid.h
2018-02-15 12:10 ` [PATCH RFC 3/4] x86: add invpcid.h Wei Liu
@ 2018-02-15 12:15 ` Andrew Cooper
2018-02-15 12:24 ` Wei Liu
2018-02-15 12:34 ` Jan Beulich
1 sibling, 1 reply; 13+ messages in thread
From: Andrew Cooper @ 2018-02-15 12:15 UTC (permalink / raw)
To: Wei Liu, Xen-devel; +Cc: Juergen Gross, Jan Beulich
On 15/02/18 12:10, Wei Liu wrote:
> Provide the functions needed for different modes.
>
> Signed-off-by: Wei Liu <wei.liu2@citrix.com>
> ---
> xen/include/asm-x86/invpcid.h | 61 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 61 insertions(+)
> create mode 100644 xen/include/asm-x86/invpcid.h
>
> diff --git a/xen/include/asm-x86/invpcid.h b/xen/include/asm-x86/invpcid.h
> new file mode 100644
> index 0000000000..7c307ecfc3
> --- /dev/null
> +++ b/xen/include/asm-x86/invpcid.h
> @@ -0,0 +1,61 @@
> +#ifndef _ASM_X86_INVPCID_H_
> +#define _ASM_X86_INVPCID_H_
> +
> +#include <xen/types.h>
> +
> +#define INVPCID_TYPE_INDIV_ADDR 0
> +#define INVPCID_TYPE_SINGLE_CTXT 1
> +#define INVPCID_TYPE_ALL_INCL_GLOBAL 2
> +#define INVPCID_TYPE_ALL_NON_GLOBAL 3
> +
> +struct invpcid_desc {
> + uint64_t pcid:12;
> + uint64_t reserved:52;
> + uint64_t addr;
> +};
> +
> +static inline void invpcid(unsigned long pcid, unsigned long addr,
> + unsigned long type)
> +{
> + struct invpcid_desc desc = { .pcid = pcid, .addr = addr };
> +
> + asm volatile ("invpcid (%0), %1"
> + : : "r" (&desc), "r" (type) : "memory" );
invpcid %[desc], %[type]
And you can use [desc] "m" (desc) for the constraint. The structure
will be built on the stack, meaning that an %rsp based memory reference
is more efficient than forcing the use of a register.
We probably also need a -DHAVE_GAS_INVPCID, as INVPCID is newer than
some of the instruction groups we already check for.
~Andrew
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH RFC 3/4] x86: add invpcid.h
2018-02-15 12:15 ` Andrew Cooper
@ 2018-02-15 12:24 ` Wei Liu
2018-02-15 12:26 ` Andrew Cooper
0 siblings, 1 reply; 13+ messages in thread
From: Wei Liu @ 2018-02-15 12:24 UTC (permalink / raw)
To: Andrew Cooper; +Cc: Juergen Gross, Xen-devel, Wei Liu, Jan Beulich
On Thu, Feb 15, 2018 at 12:15:56PM +0000, Andrew Cooper wrote:
> On 15/02/18 12:10, Wei Liu wrote:
> > Provide the functions needed for different modes.
> >
> > Signed-off-by: Wei Liu <wei.liu2@citrix.com>
> > ---
> > xen/include/asm-x86/invpcid.h | 61 +++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 61 insertions(+)
> > create mode 100644 xen/include/asm-x86/invpcid.h
> >
> > diff --git a/xen/include/asm-x86/invpcid.h b/xen/include/asm-x86/invpcid.h
> > new file mode 100644
> > index 0000000000..7c307ecfc3
> > --- /dev/null
> > +++ b/xen/include/asm-x86/invpcid.h
> > @@ -0,0 +1,61 @@
> > +#ifndef _ASM_X86_INVPCID_H_
> > +#define _ASM_X86_INVPCID_H_
> > +
> > +#include <xen/types.h>
> > +
> > +#define INVPCID_TYPE_INDIV_ADDR 0
> > +#define INVPCID_TYPE_SINGLE_CTXT 1
> > +#define INVPCID_TYPE_ALL_INCL_GLOBAL 2
> > +#define INVPCID_TYPE_ALL_NON_GLOBAL 3
> > +
> > +struct invpcid_desc {
> > + uint64_t pcid:12;
> > + uint64_t reserved:52;
> > + uint64_t addr;
> > +};
> > +
> > +static inline void invpcid(unsigned long pcid, unsigned long addr,
> > + unsigned long type)
> > +{
> > + struct invpcid_desc desc = { .pcid = pcid, .addr = addr };
> > +
> > + asm volatile ("invpcid (%0), %1"
> > + : : "r" (&desc), "r" (type) : "memory" );
>
> invpcid %[desc], %[type]
>
> And you can use [desc] "m" (desc) for the constraint. The structure
> will be built on the stack, meaning that an %rsp based memory reference
> is more efficient than forcing the use of a register.
NP.
>
> We probably also need a -DHAVE_GAS_INVPCID, as INVPCID is newer than
> some of the instruction groups we already check for.
>
Or we can just use the byte code directly -- it is the same for both 64
and 32 bit, then manually specify the ModRM byte. That's what Linux
does.
Wei.
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 13+ messages in thread* Re: [PATCH RFC 3/4] x86: add invpcid.h
2018-02-15 12:24 ` Wei Liu
@ 2018-02-15 12:26 ` Andrew Cooper
0 siblings, 0 replies; 13+ messages in thread
From: Andrew Cooper @ 2018-02-15 12:26 UTC (permalink / raw)
To: Wei Liu; +Cc: Juergen Gross, Xen-devel, Jan Beulich
On 15/02/18 12:24, Wei Liu wrote:
> On Thu, Feb 15, 2018 at 12:15:56PM +0000, Andrew Cooper wrote:
>> On 15/02/18 12:10, Wei Liu wrote:
>>> Provide the functions needed for different modes.
>>>
>>> Signed-off-by: Wei Liu <wei.liu2@citrix.com>
>>> ---
>>> xen/include/asm-x86/invpcid.h | 61 +++++++++++++++++++++++++++++++++++++++++++
>>> 1 file changed, 61 insertions(+)
>>> create mode 100644 xen/include/asm-x86/invpcid.h
>>>
>>> diff --git a/xen/include/asm-x86/invpcid.h b/xen/include/asm-x86/invpcid.h
>>> new file mode 100644
>>> index 0000000000..7c307ecfc3
>>> --- /dev/null
>>> +++ b/xen/include/asm-x86/invpcid.h
>>> @@ -0,0 +1,61 @@
>>> +#ifndef _ASM_X86_INVPCID_H_
>>> +#define _ASM_X86_INVPCID_H_
>>> +
>>> +#include <xen/types.h>
>>> +
>>> +#define INVPCID_TYPE_INDIV_ADDR 0
>>> +#define INVPCID_TYPE_SINGLE_CTXT 1
>>> +#define INVPCID_TYPE_ALL_INCL_GLOBAL 2
>>> +#define INVPCID_TYPE_ALL_NON_GLOBAL 3
>>> +
>>> +struct invpcid_desc {
>>> + uint64_t pcid:12;
>>> + uint64_t reserved:52;
>>> + uint64_t addr;
>>> +};
>>> +
>>> +static inline void invpcid(unsigned long pcid, unsigned long addr,
>>> + unsigned long type)
>>> +{
>>> + struct invpcid_desc desc = { .pcid = pcid, .addr = addr };
>>> +
>>> + asm volatile ("invpcid (%0), %1"
>>> + : : "r" (&desc), "r" (type) : "memory" );
>> invpcid %[desc], %[type]
>>
>> And you can use [desc] "m" (desc) for the constraint. The structure
>> will be built on the stack, meaning that an %rsp based memory reference
>> is more efficient than forcing the use of a register.
> NP.
>
>> We probably also need a -DHAVE_GAS_INVPCID, as INVPCID is newer than
>> some of the instruction groups we already check for.
>>
> Or we can just use the byte code directly -- it is the same for both 64
> and 32 bit, then manually specify the ModRM byte. That's what Linux
> does.
See the vmx __invept() wrapper, which is very similar, but doesn't need
the BUG() handling.
~Andrew
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH RFC 3/4] x86: add invpcid.h
2018-02-15 12:10 ` [PATCH RFC 3/4] x86: add invpcid.h Wei Liu
2018-02-15 12:15 ` Andrew Cooper
@ 2018-02-15 12:34 ` Jan Beulich
2018-02-15 12:35 ` Wei Liu
1 sibling, 1 reply; 13+ messages in thread
From: Jan Beulich @ 2018-02-15 12:34 UTC (permalink / raw)
To: Wei Liu; +Cc: Juergen Gross, Andrew Cooper, Xen-devel
>>> On 15.02.18 at 13:10, <wei.liu2@citrix.com> wrote:
> Provide the functions needed for different modes.
Do we really need all of these? Let's not have dead code sit around
and risk it becoming stale.
Jan
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH RFC 3/4] x86: add invpcid.h
2018-02-15 12:34 ` Jan Beulich
@ 2018-02-15 12:35 ` Wei Liu
2018-02-15 13:23 ` Jan Beulich
0 siblings, 1 reply; 13+ messages in thread
From: Wei Liu @ 2018-02-15 12:35 UTC (permalink / raw)
To: Jan Beulich; +Cc: Juergen Gross, Andrew Cooper, Wei Liu, Xen-devel
On Thu, Feb 15, 2018 at 05:34:26AM -0700, Jan Beulich wrote:
> >>> On 15.02.18 at 13:10, <wei.liu2@citrix.com> wrote:
> > Provide the functions needed for different modes.
>
> Do we really need all of these? Let's not have dead code sit around
> and risk it becoming stale.
>
They will be needed when we want to use PCID and INVPCID at the same
time, which seems to be the plan?
Wei.
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH RFC 3/4] x86: add invpcid.h
2018-02-15 12:35 ` Wei Liu
@ 2018-02-15 13:23 ` Jan Beulich
0 siblings, 0 replies; 13+ messages in thread
From: Jan Beulich @ 2018-02-15 13:23 UTC (permalink / raw)
To: Wei Liu; +Cc: Juergen Gross, Andrew Cooper, Xen-devel
>>> On 15.02.18 at 13:35, <wei.liu2@citrix.com> wrote:
> On Thu, Feb 15, 2018 at 05:34:26AM -0700, Jan Beulich wrote:
>> >>> On 15.02.18 at 13:10, <wei.liu2@citrix.com> wrote:
>> > Provide the functions needed for different modes.
>>
>> Do we really need all of these? Let's not have dead code sit around
>> and risk it becoming stale.
>>
>
> They will be needed when we want to use PCID and INVPCID at the same
> time, which seems to be the plan?
I know of INVPCID plans only, not any PCID ones.
Jan
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH RFC 4/4] x86: use invpcid to do global flush
2018-02-15 12:10 [PATCH RFC 0/4] Use INVPCID to flush global mappings Wei Liu
` (2 preceding siblings ...)
2018-02-15 12:10 ` [PATCH RFC 3/4] x86: add invpcid.h Wei Liu
@ 2018-02-15 12:10 ` Wei Liu
2018-02-15 15:38 ` [PATCH RFC 0/4] Use INVPCID to flush global mappings Juergen Gross
4 siblings, 0 replies; 13+ messages in thread
From: Wei Liu @ 2018-02-15 12:10 UTC (permalink / raw)
To: Xen-devel; +Cc: Juergen Gross, Andrew Cooper, Wei Liu, Jan Beulich
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
xen/arch/x86/flushtlb.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
diff --git a/xen/arch/x86/flushtlb.c b/xen/arch/x86/flushtlb.c
index 8a7a76b8ff..e4ea4f3297 100644
--- a/xen/arch/x86/flushtlb.c
+++ b/xen/arch/x86/flushtlb.c
@@ -9,6 +9,7 @@
#include <xen/sched.h>
#include <xen/softirq.h>
+#include <asm/invpcid.h>
#include <asm/flushtlb.h>
#include <asm/page.h>
@@ -120,11 +121,24 @@ unsigned int flush_area_local(const void *va, unsigned int flags)
else
{
u32 t = pre_flush();
- unsigned long cr4 = read_cr4();
- write_cr4(cr4 & ~X86_CR4_PGE);
- barrier();
- write_cr4(cr4);
+ if ( !cpu_has_invpcid )
+ {
+ unsigned long cr4 = read_cr4();
+
+ write_cr4(cr4 & ~X86_CR4_PGE);
+ barrier();
+ write_cr4(cr4);
+ }
+ else
+ {
+ /*
+ * Using invpcid to flush all mappings works
+ * regardless of whether PCID is enabled or not.
+ * It is faster than read-modify-write CR4.
+ */
+ invpcid_flush_all();
+ }
post_flush(t);
}
--
2.11.0
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply related [flat|nested] 13+ messages in thread* Re: [PATCH RFC 0/4] Use INVPCID to flush global mappings
2018-02-15 12:10 [PATCH RFC 0/4] Use INVPCID to flush global mappings Wei Liu
` (3 preceding siblings ...)
2018-02-15 12:10 ` [PATCH RFC 4/4] x86: use invpcid to do global flush Wei Liu
@ 2018-02-15 15:38 ` Juergen Gross
4 siblings, 0 replies; 13+ messages in thread
From: Juergen Gross @ 2018-02-15 15:38 UTC (permalink / raw)
To: Wei Liu, Xen-devel; +Cc: Andrew Cooper, Jan Beulich
On 15/02/18 13:10, Wei Liu wrote:
> I wrote these patches sometime ago to explore PCID and INVPCID. I haven't
> thought through whether how to use both in Xen yet. But seeing Juergen laid out
> his thought on PCID and INVPCID I think some of the patches can be useful.
>
> I had done some benchmark on the speed in one of my older branch by inserting
> some trace points before and after the flush. It showed that twiddling CR4.PGE
> is 3 to 5 times slower than invpcid.
>
> This series is in incomplete -- obviously we have CR4.PGE twiddling in a few
> other places. But if you think it is beneficial I can try to convert those
> places as well.
I just did a little experiment by replacing the %cr4 based TLB flush in
Jan's XPTI patches by invpcid, on top of my last XPTI speedup patch (no
fancy ALTERNATIVE, just a plain replacement).
Doing a parallel build of the hypervisor in dom0 showed following data:
real user sys
xpti=no 61.2 167.7 71.9
xpti=yes 112.1 170.1 141.8
+ my speedup 103.0 171.2 131.2
+ invpcid 99.0 170.2 122.0
So system time reduction due to invpcid is quite nice.
Juergen
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 13+ messages in thread