* [kvm-unit-tests PATCH] x86: Fix breakage of fw_cfg for 32-bit unit tests
@ 2019-08-22 23:50 Sean Christopherson
2019-08-22 23:55 ` Nadav Amit
0 siblings, 1 reply; 3+ messages in thread
From: Sean Christopherson @ 2019-08-22 23:50 UTC (permalink / raw)
To: Paolo Bonzini, Radim Krčmář; +Cc: kvm, Nadav Amit
Ensure the fw_cfg overrides are parsed prior consuming any of said
overrides. fwcfg_get_u() treats zero as a valid overide value, which
is slightly problematic since the overrides are in the .bss and thus
initialized to zero.
Add a limit check when indexing fw_override so that future code doesn't
spontaneously explode.
Cc: Nadav Amit <nadav.amit@gmail.com>
Fixes: 03b1e4570f967 ("x86: Support environments without test-devices")
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
lib/x86/fwcfg.c | 10 ++++++++--
lib/x86/fwcfg.h | 2 --
x86/cstart64.S | 2 --
3 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/lib/x86/fwcfg.c b/lib/x86/fwcfg.c
index d8d797f..06ef62c 100644
--- a/lib/x86/fwcfg.c
+++ b/lib/x86/fwcfg.c
@@ -5,10 +5,11 @@
static struct spinlock lock;
static long fw_override[FW_CFG_MAX_ENTRY];
+static bool fw_override_done;
bool no_test_device;
-void read_cfg_override(void)
+static void read_cfg_override(void)
{
const char *str;
int i;
@@ -26,6 +27,8 @@ void read_cfg_override(void)
if ((str = getenv("TEST_DEVICE")))
no_test_device = !atol(str);
+
+ fw_override_done = true;
}
static uint64_t fwcfg_get_u(uint16_t index, int bytes)
@@ -34,7 +37,10 @@ static uint64_t fwcfg_get_u(uint16_t index, int bytes)
uint8_t b;
int i;
- if (fw_override[index] >= 0)
+ if (!fw_override_done)
+ read_cfg_override();
+
+ if (index < FW_CFG_MAX_ENTRY && fw_override[index] >= 0)
return fw_override[index];
spin_lock(&lock);
diff --git a/lib/x86/fwcfg.h b/lib/x86/fwcfg.h
index 88dc7a7..2f17461 100644
--- a/lib/x86/fwcfg.h
+++ b/lib/x86/fwcfg.h
@@ -36,8 +36,6 @@
extern bool no_test_device;
-void read_cfg_override(void);
-
static inline bool test_device_enabled(void)
{
return !no_test_device;
diff --git a/x86/cstart64.S b/x86/cstart64.S
index 23c1bd4..d4e4652 100644
--- a/x86/cstart64.S
+++ b/x86/cstart64.S
@@ -254,8 +254,6 @@ start64:
mov %rax, __args(%rip)
call __setup_args
- /* Read the configuration before running smp_init */
- call read_cfg_override
call smp_init
call enable_x2apic
--
2.22.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [kvm-unit-tests PATCH] x86: Fix breakage of fw_cfg for 32-bit unit tests
2019-08-22 23:50 [kvm-unit-tests PATCH] x86: Fix breakage of fw_cfg for 32-bit unit tests Sean Christopherson
@ 2019-08-22 23:55 ` Nadav Amit
2019-08-22 23:56 ` Sean Christopherson
0 siblings, 1 reply; 3+ messages in thread
From: Nadav Amit @ 2019-08-22 23:55 UTC (permalink / raw)
To: Sean Christopherson; +Cc: Paolo Bonzini, Radim Krčmář, kvm
> On Aug 22, 2019, at 4:50 PM, Sean Christopherson <sean.j.christopherson@intel.com> wrote:
>
> Ensure the fw_cfg overrides are parsed prior consuming any of said
> overrides. fwcfg_get_u() treats zero as a valid overide value, which
> is slightly problematic since the overrides are in the .bss and thus
> initialized to zero.
>
> Add a limit check when indexing fw_override so that future code doesn't
> spontaneously explode.
>
> Cc: Nadav Amit <nadav.amit@gmail.com>
> Fixes: 03b1e4570f967 ("x86: Support environments without test-devices")
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> lib/x86/fwcfg.c | 10 ++++++++--
> lib/x86/fwcfg.h | 2 --
> x86/cstart64.S | 2 --
> 3 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/lib/x86/fwcfg.c b/lib/x86/fwcfg.c
> index d8d797f..06ef62c 100644
> --- a/lib/x86/fwcfg.c
> +++ b/lib/x86/fwcfg.c
> @@ -5,10 +5,11 @@
> static struct spinlock lock;
>
> static long fw_override[FW_CFG_MAX_ENTRY];
> +static bool fw_override_done;
>
> bool no_test_device;
>
> -void read_cfg_override(void)
> +static void read_cfg_override(void)
> {
> const char *str;
> int i;
> @@ -26,6 +27,8 @@ void read_cfg_override(void)
>
> if ((str = getenv("TEST_DEVICE")))
> no_test_device = !atol(str);
> +
> + fw_override_done = true;
> }
>
> static uint64_t fwcfg_get_u(uint16_t index, int bytes)
> @@ -34,7 +37,10 @@ static uint64_t fwcfg_get_u(uint16_t index, int bytes)
> uint8_t b;
> int i;
>
> - if (fw_override[index] >= 0)
> + if (!fw_override_done)
> + read_cfg_override();
> +
> + if (index < FW_CFG_MAX_ENTRY && fw_override[index] >= 0)
> return fw_override[index];
How did that happen? I remember I tested this code with KVM..
Anyhow,
Reviewed-by: Nadav Amit <nadav.amit@gmail.com>
Thanks for fixing it.
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [kvm-unit-tests PATCH] x86: Fix breakage of fw_cfg for 32-bit unit tests
2019-08-22 23:55 ` Nadav Amit
@ 2019-08-22 23:56 ` Sean Christopherson
0 siblings, 0 replies; 3+ messages in thread
From: Sean Christopherson @ 2019-08-22 23:56 UTC (permalink / raw)
To: Nadav Amit; +Cc: Paolo Bonzini, Radim Krčmář, kvm
On Thu, Aug 22, 2019 at 04:55:14PM -0700, Nadav Amit wrote:
> > On Aug 22, 2019, at 4:50 PM, Sean Christopherson <sean.j.christopherson@intel.com> wrote:
> >
> > Ensure the fw_cfg overrides are parsed prior consuming any of said
> > overrides. fwcfg_get_u() treats zero as a valid overide value, which
> > is slightly problematic since the overrides are in the .bss and thus
> > initialized to zero.
> >
> > Add a limit check when indexing fw_override so that future code doesn't
> > spontaneously explode.
> >
> > Cc: Nadav Amit <nadav.amit@gmail.com>
> > Fixes: 03b1e4570f967 ("x86: Support environments without test-devices")
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > ---
> > lib/x86/fwcfg.c | 10 ++++++++--
> > lib/x86/fwcfg.h | 2 --
> > x86/cstart64.S | 2 --
> > 3 files changed, 8 insertions(+), 6 deletions(-)
> >
> > diff --git a/lib/x86/fwcfg.c b/lib/x86/fwcfg.c
> > index d8d797f..06ef62c 100644
> > --- a/lib/x86/fwcfg.c
> > +++ b/lib/x86/fwcfg.c
> > @@ -5,10 +5,11 @@
> > static struct spinlock lock;
> >
> > static long fw_override[FW_CFG_MAX_ENTRY];
> > +static bool fw_override_done;
> >
> > bool no_test_device;
> >
> > -void read_cfg_override(void)
> > +static void read_cfg_override(void)
> > {
> > const char *str;
> > int i;
> > @@ -26,6 +27,8 @@ void read_cfg_override(void)
> >
> > if ((str = getenv("TEST_DEVICE")))
> > no_test_device = !atol(str);
> > +
> > + fw_override_done = true;
> > }
> >
> > static uint64_t fwcfg_get_u(uint16_t index, int bytes)
> > @@ -34,7 +37,10 @@ static uint64_t fwcfg_get_u(uint16_t index, int bytes)
> > uint8_t b;
> > int i;
> >
> > - if (fw_override[index] >= 0)
> > + if (!fw_override_done)
> > + read_cfg_override();
> > +
> > + if (index < FW_CFG_MAX_ENTRY && fw_override[index] >= 0)
> > return fw_override[index];
>
> How did that happen? I remember I tested this code with KVM..
It only breaks 32-bit KVM.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-08-22 23:50 [kvm-unit-tests PATCH] x86: Fix breakage of fw_cfg for 32-bit unit tests Sean Christopherson
2019-08-22 23:55 ` Nadav Amit
2019-08-22 23:56 ` Sean Christopherson
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