On 06.03.20 09:20, Jan Beulich wrote:
On 06.03.2020 07:42, Jürgen Groß wrote:
On 05.03.20 09:26, Jan Beulich wrote:
On 05.03.2020 07:01, Jürgen Groß wrote:
On 04.03.20 17:56, Jan Beulich wrote:
On 04.03.2020 17:31, Jürgen Groß wrote:
On 04.03.20 16:19, Jan Beulich wrote:
On 04.03.2020 16:07, Jürgen Groß wrote:
On 04.03.20 12:32, Jan Beulich wrote:
On 26.02.2020 13:47, Juergen Gross wrote:
+static void update_ept_param_append(const char *str, int val)
+{
+ char *pos = opt_ept_setting + strlen(opt_ept_setting);
+
+ snprintf(pos, sizeof(opt_ept_setting) - (pos - opt_ept_setting),
+ ",%s=%d", str, val);
+}
+
+static void update_ept_param(void)
+{
+ snprintf(opt_ept_setting, sizeof(opt_ept_setting), "pml=%d", opt_ept_pml);
+ if ( opt_ept_ad >= 0 )
+ update_ept_param_append("ad", opt_ept_ad);
This won't correctly reflect reality: If you look at
vmx_init_vmcs_config(), even a negative value means "true" here,
unless on a specific Atom model. I think init_ept_param() wants
to have that erratum workaround logic moved there, such that
you can then assme the value to be non-negative here.
But isn't not mentioning it in the -1 case correct? -1 means: do the
correct thing on the current hardware.
Well, I think the output here should represent effective settings,
The minimum requirement is to reflect the effective parameters, like
cmdline is doing for boot-time only parameters. With runtime parameters
we had no way of telling what was set, and this is now possible.
and a sub-item should be suppressed only if a setting has no effect
at all in the current setup, like ...
+ if ( opt_ept_exec_sp >= 0 )
+ update_ept_param_append("exec-sp", opt_ept_exec_sp);
I agree for this one - if the value is still -1, it has neither
been set nor is its value of any interest.
... here.
I think we should not mix up specified parameters and effective
settings. In case an effective setting is of common interest it should
be reported via a specific node (like e.g. specific mitigation settings
where the cmdline is not providing enough details).
But then a boolean option that wasn't specified on the command line
should produce no output at all. And hence we'd need a way to tell
whether an option was set from command line for _all_ of them. I
don't think this would be very helpful.
I disagree here.
This is important only for cases where the hypervisor treats the
parameter as a tristate: true/false/unspecified. In all cases where
the bool value is really true or false it can be reported as such.
The problem I'm having with this is the resulting inconsistency:
When we write the variable with 0 or 1 in case we find it to be
-1 after command line parsing, the externally visible effect will
be different from the case where we leave it to be -1 yet still
treat it as (pseudo-)boolean. This, however, is an implementation
detail, while imo the hypfs presentation should not depend on
such implementation details.
Reporting 0/1 for e.g. "ad" if opt_ept_ad==-1 would add a latent problem
if any other action would be derived from the parameter variable being
-1.
So either opt_ept_ad should be modified to change it to 0/1 instead of
only setting the VCMS flag,
That's what I did suggest.
or the logic should be kept as is in this
patch. IMO changing the setting of opt_ept_ad should be done in another
patch if this is really wanted.
And of course I don't mind at all doing so in a prereq patch.
It's just that the patch here provides a good place _where_ to
actually do such an adjustment.
I was thinking of something like this:
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -313,12 +313,12 @@ static int vmx_init_vmcs_config(void)
{
rdmsrl(MSR_IA32_VMX_EPT_VPID_CAP, _vmx_ept_vpid_cap);
+ if ( /* Work around Erratum AVR41 on Avoton processors. */
+ boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model == 0x4d &&
+ opt_ept_ad < 0 )
+ opt_ept_ad = 0;
if ( !opt_ept_ad )
_vmx_ept_vpid_cap &= ~VMX_EPT_AD_BIT;
- else if ( /* Work around Erratum AVR41 on Avoton processors. */
- boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model == 0x4d &&
- opt_ept_ad < 0 )
- _vmx_ept_vpid_cap &= ~VMX_EPT_AD_BIT;
/*
* Additional sanity checking before using EPT:
And I was specifically hoping to avoid doing this in a non-__init
function.
Should be fairly easy (see attached patch).
Juergen
>From 32f307522c2044130bb8ed66189efc411c540103 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgr...@suse.com>
Date: Fri, 6 Mar 2020 07:30:36 +0100
Subject: [PATCH] xen/vmx: let opt_ept_ad always reflect the current setting
In case opt_ept_ad has not been set explicitly by the user via command
line or runtime parameter, it is treated as "no" on Avoton cpus.
Change that handling by setting opt_ept_ad to 0 for this cpu type
explicitly if no user value has been set.
By putting this into the (renamed) boot time initialization of vmcs.c
_vmx_cpu_up() can be made static.
Signed-off-by: Juergen Gross <jgr...@suse.com>
---
xen/arch/x86/hvm/vmx/vmcs.c | 22 +++++++++++++++-------
xen/arch/x86/hvm/vmx/vmx.c | 4 +---
xen/include/asm-x86/hvm/vmx/vmcs.h | 3 +--
3 files changed, 17 insertions(+), 12 deletions(-)
diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 4c23645454..24f2bd6e43 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -315,10 +315,6 @@ static int vmx_init_vmcs_config(void)
if ( !opt_ept_ad )
_vmx_ept_vpid_cap &= ~VMX_EPT_AD_BIT;
- else if ( /* Work around Erratum AVR41 on Avoton processors. */
- boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model == 0x4d &&
- opt_ept_ad < 0 )
- _vmx_ept_vpid_cap &= ~VMX_EPT_AD_BIT;
/*
* Additional sanity checking before using EPT:
@@ -652,7 +648,7 @@ void vmx_cpu_dead(unsigned int cpu)
vmx_pi_desc_fixup(cpu);
}
-int _vmx_cpu_up(bool bsp)
+static int _vmx_cpu_up(bool bsp)
{
u32 eax, edx;
int rc, bios_locked, cpu = smp_processor_id();
@@ -2108,9 +2104,21 @@ static void vmcs_dump(unsigned char ch)
printk("**************************************\n");
}
-void __init setup_vmcs_dump(void)
+int __init vmx_vmcs_init(void)
{
- register_keyhandler('v', vmcs_dump, "dump VT-x VMCSs", 1);
+ int ret;
+
+ if ( opt_ept_ad < 0 )
+ /* Work around Erratum AVR41 on Avoton processors. */
+ opt_ept_ad = (boot_cpu_data.x86 == 6 &&
+ boot_cpu_data.x86_model == 0x4d) ? 0 : 1;
+
+ ret = _vmx_cpu_up(true);
+
+ if ( !ret )
+ register_keyhandler('v', vmcs_dump, "dump VT-x VMCSs", 1);
+
+ return ret;
}
static void __init __maybe_unused build_assertions(void)
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index d265ed46ad..d0ad2ed879 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2478,7 +2478,7 @@ const struct hvm_function_table * __init start_vmx(void)
{
set_in_cr4(X86_CR4_VMXE);
- if ( _vmx_cpu_up(true) )
+ if ( vmx_vmcs_init() )
{
printk("VMX: failed to initialise.\n");
return NULL;
@@ -2549,8 +2549,6 @@ const struct hvm_function_table * __init start_vmx(void)
vmx_function_table.get_guest_bndcfgs = vmx_get_guest_bndcfgs;
}
- setup_vmcs_dump();
-
lbr_tsx_fixup_check();
bdf93_fixup_check();
diff --git a/xen/include/asm-x86/hvm/vmx/vmcs.h b/xen/include/asm-x86/hvm/vmx/vmcs.h
index be4661a929..b346a132e2 100644
--- a/xen/include/asm-x86/hvm/vmx/vmcs.h
+++ b/xen/include/asm-x86/hvm/vmx/vmcs.h
@@ -21,11 +21,10 @@
#include <asm/hvm/io.h>
extern void vmcs_dump_vcpu(struct vcpu *v);
-extern void setup_vmcs_dump(void);
+extern int vmx_vmcs_init(void);
extern int vmx_cpu_up_prepare(unsigned int cpu);
extern void vmx_cpu_dead(unsigned int cpu);
extern int vmx_cpu_up(void);
-extern int _vmx_cpu_up(bool bsp);
extern void vmx_cpu_down(void);
struct vmcs_struct {
--
2.16.4
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