[PATCH] platform/x86: intel_pmc_core: Do not ioremap RAM

[PATCH] platform/x86: intel_pmc_core: Do not ioremap RAM

[M. Vefa Bicakci]

On a Xen-based PVH virtual machine with more than 4 GiB of RAM,
intel_pmc_core fails initialization with the following warning message
from the kernel, indicating that the driver is attempting to ioremap
RAM:

  ------------[ cut here ]------------
  ioremap on RAM at 0x00000000fe000000 - 0x00000000fe001fff
  WARNING: CPU: 1 PID: 434 at arch/x86/mm/ioremap.c:186 __ioremap_caller.constprop.0+0x2aa/0x2c0
  Modules linked in: intel_pmc_core_pltdrv(+) xen_netfront(+) intel_pmc_core \
    crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel \
    intel_rapl_perf pcspkr binfmt_misc u2mfn(O) xenfs xen_gntdev \
    xen_gntalloc xen_blkback xen_privcmd xen_evtchn ip_tables overlay \
    xen_blkfront
  CPU: 1 PID: 434 Comm: systemd-udevd Tainted: G           O      5.3.0-rc3-next-20190809-1 #2
  RIP: 0010:__ioremap_caller.constprop.0+0x2aa/0x2c0
  Code: 05 0f c9 1b 01 49 09 c6 e9 8e fe ff ff 48 8d 54 24 28 48 c7 c7 68 87 0a 82 c6 05 c4 23 2b 01 01 48 8d 74 24 18 e8 d4 4a 06 00 <0f> 0b 45 31 ff e9 fe fe ff ff e8 e7 47 06 00 0f 1f 80 00 00 00 00
  RSP: 0018:ffffc900002dfa20 EFLAGS: 00010282
  RAX: 0000000000000000 RBX: ffffffffc0107000 RCX: 0000000000000006
  RDX: 0000000000000007 RSI: 0000000000000092 RDI: ffff88813bb17540
  RBP: 00000000fe000000 R08: 000000000000015f R09: 000000000000000a
  R10: 000000000000000a R11: ffffc900002df8da R12: 0000000000002000
  R13: 0000000000000000 R14: 0000000000000002 R15: ffffffff822da3a0
  FS:  000072ecce666940(0000) GS:ffff88813bb00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000785be7346d20 CR3: 000000000d872001 CR4: 00000000003606e0
  Call Trace:
   ? pmc_core_probe+0x87/0x2d0 [intel_pmc_core]
   pmc_core_probe+0x87/0x2d0 [intel_pmc_core]
   platform_drv_probe+0x35/0x80
   really_probe+0x298/0x3c0
   driver_probe_device+0x7a/0x100
   ? driver_allows_async_probing+0x50/0x50
   bus_for_each_drv+0x8f/0xd0
   __device_attach+0xf0/0x170
   bus_probe_device+0x8e/0xa0
   device_add+0x692/0x7e0
   platform_device_add+0xe9/0x240
   ? 0xffffffffc00ec000
   do_one_initcall+0x59/0x214
   do_init_module+0x5c/0x230
   load_module+0x258d/0x2840
   ? __do_sys_finit_module+0xbb/0x120
   __do_sys_finit_module+0xbb/0x120
   do_syscall_64+0x5f/0x1a0
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x72eccf662fad
  Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ab 9e 0c 00 f7 d8 64 89 01 48
  RSP: 002b:00007ffd3710d018 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
  RAX: ffffffffffffffda RBX: 000060ab8fda2530 RCX: 000072eccf662fad
  RDX: 0000000000000000 RSI: 000072eccf2bd84d RDI: 0000000000000017
  RBP: 0000000000020000 R08: 0000000000000000 R09: 0000000000000007
  R10: 0000000000000017 R11: 0000000000000246 R12: 000072eccf2bd84d
  R13: 0000000000000000 R14: 000060ab8fd9b5e0 R15: 0000000000000007
  ---[ end trace 5e5421608729d6f4 ]---

This issue appears to manifest itself because of the following fallback
mechanism in the driver:

	if (lpit_read_residency_count_address(&slp_s0_addr))
		pmcdev->base_addr = PMC_BASE_ADDR_DEFAULT;

The validity of address PMC_BASE_ADDR_DEFAULT (i.e., 0xFE000000) is not
verified by the driver, which is what this patch introduces. With this
patch, if address PMC_BASE_ADDR_DEFAULT is in RAM, then the driver will
not attempt to ioremap the aforementioned address.

Signed-off-by: M. Vefa Bicakci <m.v.b@runbox.com>
---
 drivers/platform/x86/intel_pmc_core.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/x86/intel_pmc_core.c b/drivers/platform/x86/intel_pmc_core.c
index c510d0d72475..3b6b8dcc4767 100644
--- a/drivers/platform/x86/intel_pmc_core.c
+++ b/drivers/platform/x86/intel_pmc_core.c
@@ -878,10 +878,14 @@ static int pmc_core_probe(struct platform_device *pdev)
 	if (pmcdev->map == &spt_reg_map && !pci_dev_present(pmc_pci_ids))
 		pmcdev->map = &cnp_reg_map;
 
-	if (lpit_read_residency_count_address(&slp_s0_addr))
+	if (lpit_read_residency_count_address(&slp_s0_addr)) {
 		pmcdev->base_addr = PMC_BASE_ADDR_DEFAULT;
-	else
+
+		if (page_is_ram(PHYS_PFN(pmcdev->base_addr)))
+			return -ENODEV;
+	} else {
 		pmcdev->base_addr = slp_s0_addr - pmcdev->map->slp_s0_offset;
+	}
 
 	pmcdev->regbase = ioremap(pmcdev->base_addr,
 				  pmcdev->map->regmap_length);
-- 
2.21.0

[PATCH] platform/x86: intel_pmc_core_pltdrv: Module removal warning fix

[M. Vefa Bicakci]

Prior to this commit, removing the intel_pmc_core_pltdrv module
would cause the following warning:

  ------------[ cut here ]------------
  Device 'intel_pmc_core.0' does not have a release() function, \
    it is broken and must be fixed. See Documentation/kobject.txt.
  WARNING: CPU: 0 PID: 2202 at drivers/base/core.c:1238 device_release+0x6f/0x80
  Modules linked in: fuse intel_rapl_msr ip6table_filter ip6_tables ipt_REJECT \
    nf_reject_ipv4 xt_conntrack iptable_filter xt_MASQUERADE iptable_nat nf_nat \
    nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c intel_rapl_common \
    intel_pmc_core_pltdrv(-) xen_netfront intel_pmc_core crct10dif_pclmul \
    crc32_pclmul crc32c_intel ghash_clmulni_intel intel_rapl_perf pcspkr binfmt_misc \
    u2mfn(O) xenfs xen_gntdev xen_gntalloc xen_blkback xen_privcmd xen_evtchn \
    ip_tables overlay xen_blkfront
  CPU: 0 PID: 2202 Comm: rmmod Tainted: G        W  O      5.3.0-rc3-next-20190809-1 #2
  RIP: 0010:device_release+0x6f/0x80
  Code: 48 8b 85 c0 02 00 00 48 85 c0 74 09 48 8b 40 40 48 85 c0 75 c6 48 8b 75 50 48 85 f6 74 10 48 c7 c7 58 68 12 82 e8 5f 62 a9 ff <0f> 0b eb b5 48 8b 75 00 eb ea 0f 1f 80 00 00 00 00 0f 1f 44 00 00
  RSP: 0018:ffffc90000763ea8 EFLAGS: 00010286
  RAX: 0000000000000000 RBX: ffffffff822da080 RCX: 0000000000000006
  RDX: 0000000000000007 RSI: 0000000000000082 RDI: ffff88813ba17540
  RBP: ffffffffc0107010 R08: 0000000000000195 R09: 000000000000000d
  R10: 000000000000000a R11: ffffc90000763d65 R12: ffff88800c9e9000
  R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
  FS:  000071250bf142c0(0000) GS:ffff88813ba00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 000060ab8fd82d49 CR3: 00000001273ba004 CR4: 00000000003606f0
  Call Trace:
   kobject_put+0x85/0x1b0
   __x64_sys_delete_module+0x14b/0x270
   do_syscall_64+0x5f/0x1a0
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x71250c031c6b
  Code: 73 01 c3 48 8b 0d 1d 42 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ed 41 0c 00 f7 d8 64 89 01 48
  RSP: 002b:00007ffec29e6038 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
  RAX: ffffffffffffffda RBX: 00006040bc3e07b0 RCX: 000071250c031c6b
  RDX: 000000000000000a RSI: 0000000000000800 RDI: 00006040bc3e0818
  RBP: 00007ffec29e6088 R08: 1999999999999999 R09: 0000000000000000
  R10: 000071250c0a6ac0 R11: 0000000000000206 R12: 00007ffec29e6250
  R13: 00007ffec29e67b7 R14: 00006040bc3e0260 R15: 00007ffec29e6090
  ---[ end trace 5e5421608729d6f5 ]---

This commit hence adds an empty release function for the driver.

Signed-off-by: M. Vefa Bicakci <m.v.b@runbox.com>
---
 drivers/platform/x86/intel_pmc_core_pltdrv.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/platform/x86/intel_pmc_core_pltdrv.c b/drivers/platform/x86/intel_pmc_core_pltdrv.c
index a8754a6db1b8..186540014c48 100644
--- a/drivers/platform/x86/intel_pmc_core_pltdrv.c
+++ b/drivers/platform/x86/intel_pmc_core_pltdrv.c
@@ -18,8 +18,16 @@
 #include <asm/cpu_device_id.h>
 #include <asm/intel-family.h>
 
+static void intel_pmc_core_release(struct device *dev)
+{
+	/* Nothing to do. */
+}
+
 static struct platform_device pmc_core_device = {
 	.name = "intel_pmc_core",
+	.dev  = {
+		.release = intel_pmc_core_release,
+	},
 };
 
 /*
-- 
2.21.0

Re: [PATCH] platform/x86: intel_pmc_core: Do not ioremap RAM

[Andy Shevchenko]

On Fri, Aug 16, 2019 at 4:42 AM M. Vefa Bicakci <m.v.b@runbox.com> wrote:
>
> On a Xen-based PVH virtual machine with more than 4 GiB of RAM,
> intel_pmc_core fails initialization with the following warning message
> from the kernel, indicating that the driver is attempting to ioremap
> RAM:
>
>   ------------[ cut here ]------------
>   ioremap on RAM at 0x00000000fe000000 - 0x00000000fe001fff

> This issue appears to manifest itself because of the following fallback
> mechanism in the driver:
>
>         if (lpit_read_residency_count_address(&slp_s0_addr))
>                 pmcdev->base_addr = PMC_BASE_ADDR_DEFAULT;
>
> The validity of address PMC_BASE_ADDR_DEFAULT (i.e., 0xFE000000) is not
> verified by the driver, which is what this patch introduces. With this
> patch, if address PMC_BASE_ADDR_DEFAULT is in RAM, then the driver will
> not attempt to ioremap the aforementioned address.

Thank you for the patch.
Is there anything preventing us to use memremap() in such case?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] platform/x86: intel_pmc_core: Do not ioremap RAM

[M. Vefa Bicakci]

On Fri, 16 Aug 2019 12:21:58 +0300
Andy Shevchenko <andy.shevchenko@gmail.com> wrote:

> On Fri, Aug 16, 2019 at 4:42 AM M. Vefa Bicakci <m.v.b@runbox.com> wrote:
> >
> > On a Xen-based PVH virtual machine with more than 4 GiB of RAM,
> > intel_pmc_core fails initialization with the following warning message
> > from the kernel, indicating that the driver is attempting to ioremap
> > RAM:
> >
> >   ------------[ cut here ]------------
> >   ioremap on RAM at 0x00000000fe000000 - 0x00000000fe001fff  
> 
> > This issue appears to manifest itself because of the following fallback
> > mechanism in the driver:
> >
> >         if (lpit_read_residency_count_address(&slp_s0_addr))
> >                 pmcdev->base_addr = PMC_BASE_ADDR_DEFAULT;
> >
> > The validity of address PMC_BASE_ADDR_DEFAULT (i.e., 0xFE000000) is not
> > verified by the driver, which is what this patch introduces. With this
> > patch, if address PMC_BASE_ADDR_DEFAULT is in RAM, then the driver will
> > not attempt to ioremap the aforementioned address.  
> 
> Thank you for the patch.

Hello Andy,

Thank you for reviewing the patch!

> Is there anything preventing us to use memremap() in such case?

I re-read the documentation for memremap a few times along with taking
a look at its code, but I think I am missing an important piece of
information. As I understand it, depending on its flags, memremap would
allow a section of RAM to be mapped for the PMC driver.

The intention with this patch is to prevent the driver from being
instantiated when the default/fallback memory address is in RAM, as
this issue occurs with a non-administrative virtual machine (domU in
Xen terminology) that does not simulate or pass-through a corresponding
PMC device.

I think that I have misunderstood your review comment though, so I
would apppreciate it if you could elaborate.

Thanks again for reviewing the patch,

Vefa

(Please note that my next reply may be delayed by about 10 hours.)

Re: [PATCH] platform/x86: intel_pmc_core_pltdrv: Module removal warning fix

[Andy Shevchenko]

On Fri, Aug 16, 2019 at 4:42 AM M. Vefa Bicakci <m.v.b@runbox.com> wrote:
>
> Prior to this commit, removing the intel_pmc_core_pltdrv module
> would cause the following warning:
>
>   ------------[ cut here ]------------
>   Device 'intel_pmc_core.0' does not have a release() function, \
>     it is broken and must be fixed. See Documentation/kobject.txt.
>   WARNING: CPU: 0 PID: 2202 at drivers/base/core.c:1238 device_release+0x6f/0x80
>   Modules linked in: fuse intel_rapl_msr ip6table_filter ip6_tables ipt_REJECT \
>     nf_reject_ipv4 xt_conntrack iptable_filter xt_MASQUERADE iptable_nat nf_nat \
>     nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c intel_rapl_common \
>     intel_pmc_core_pltdrv(-) xen_netfront intel_pmc_core crct10dif_pclmul \
>     crc32_pclmul crc32c_intel ghash_clmulni_intel intel_rapl_perf pcspkr binfmt_misc \
>     u2mfn(O) xenfs xen_gntdev xen_gntalloc xen_blkback xen_privcmd xen_evtchn \
>     ip_tables overlay xen_blkfront
>   CPU: 0 PID: 2202 Comm: rmmod Tainted: G        W  O      5.3.0-rc3-next-20190809-1 #2
>   RIP: 0010:device_release+0x6f/0x80
>   Code: 48 8b 85 c0 02 00 00 48 85 c0 74 09 48 8b 40 40 48 85 c0 75 c6 48 8b 75 50 48 85 f6 74 10 48 c7 c7 58 68 12 82 e8 5f 62 a9 ff <0f> 0b eb b5 48 8b 75 00 eb ea 0f 1f 80 00 00 00 00 0f 1f 44 00 00
>   RSP: 0018:ffffc90000763ea8 EFLAGS: 00010286
>   RAX: 0000000000000000 RBX: ffffffff822da080 RCX: 0000000000000006
>   RDX: 0000000000000007 RSI: 0000000000000082 RDI: ffff88813ba17540
>   RBP: ffffffffc0107010 R08: 0000000000000195 R09: 000000000000000d
>   R10: 000000000000000a R11: ffffc90000763d65 R12: ffff88800c9e9000
>   R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>   FS:  000071250bf142c0(0000) GS:ffff88813ba00000(0000) knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 000060ab8fd82d49 CR3: 00000001273ba004 CR4: 00000000003606f0
>   Call Trace:
>    kobject_put+0x85/0x1b0
>    __x64_sys_delete_module+0x14b/0x270
>    do_syscall_64+0x5f/0x1a0
>    entry_SYSCALL_64_after_hwframe+0x44/0xa9
>   RIP: 0033:0x71250c031c6b
>   Code: 73 01 c3 48 8b 0d 1d 42 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ed 41 0c 00 f7 d8 64 89 01 48
>   RSP: 002b:00007ffec29e6038 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
>   RAX: ffffffffffffffda RBX: 00006040bc3e07b0 RCX: 000071250c031c6b
>   RDX: 000000000000000a RSI: 0000000000000800 RDI: 00006040bc3e0818
>   RBP: 00007ffec29e6088 R08: 1999999999999999 R09: 0000000000000000
>   R10: 000071250c0a6ac0 R11: 0000000000000206 R12: 00007ffec29e6250
>   R13: 00007ffec29e67b7 R14: 00006040bc3e0260 R15: 00007ffec29e6090
>   ---[ end trace 5e5421608729d6f5 ]---
>
> This commit hence adds an empty release function for the driver.
>

Pushed to my review and testing queue, thanks!

P.S. I cut unnecessary output off.

> Signed-off-by: M. Vefa Bicakci <m.v.b@runbox.com>
> ---
>  drivers/platform/x86/intel_pmc_core_pltdrv.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/platform/x86/intel_pmc_core_pltdrv.c b/drivers/platform/x86/intel_pmc_core_pltdrv.c
> index a8754a6db1b8..186540014c48 100644
> --- a/drivers/platform/x86/intel_pmc_core_pltdrv.c
> +++ b/drivers/platform/x86/intel_pmc_core_pltdrv.c
> @@ -18,8 +18,16 @@
>  #include <asm/cpu_device_id.h>
>  #include <asm/intel-family.h>
>
> +static void intel_pmc_core_release(struct device *dev)
> +{
> +       /* Nothing to do. */
> +}
> +
>  static struct platform_device pmc_core_device = {
>         .name = "intel_pmc_core",
> +       .dev  = {
> +               .release = intel_pmc_core_release,
> +       },
>  };
>
>  /*
> --
> 2.21.0
>


-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] platform/x86: intel_pmc_core: Do not ioremap RAM

[Andy Shevchenko]

On Fri, Aug 16, 2019 at 4:42 AM M. Vefa Bicakci <m.v.b@runbox.com> wrote:
>
> On a Xen-based PVH virtual machine with more than 4 GiB of RAM,
> intel_pmc_core fails initialization with the following warning message
> from the kernel, indicating that the driver is attempting to ioremap
> RAM:
>
>   ------------[ cut here ]------------
>   ioremap on RAM at 0x00000000fe000000 - 0x00000000fe001fff
>   WARNING: CPU: 1 PID: 434 at arch/x86/mm/ioremap.c:186 __ioremap_caller.constprop.0+0x2aa/0x2c0
>   Modules linked in: intel_pmc_core_pltdrv(+) xen_netfront(+) intel_pmc_core \
>     crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel \
>     intel_rapl_perf pcspkr binfmt_misc u2mfn(O) xenfs xen_gntdev \
>     xen_gntalloc xen_blkback xen_privcmd xen_evtchn ip_tables overlay \
>     xen_blkfront
>   CPU: 1 PID: 434 Comm: systemd-udevd Tainted: G           O      5.3.0-rc3-next-20190809-1 #2
>   RIP: 0010:__ioremap_caller.constprop.0+0x2aa/0x2c0
>   Code: 05 0f c9 1b 01 49 09 c6 e9 8e fe ff ff 48 8d 54 24 28 48 c7 c7 68 87 0a 82 c6 05 c4 23 2b 01 01 48 8d 74 24 18 e8 d4 4a 06 00 <0f> 0b 45 31 ff e9 fe fe ff ff e8 e7 47 06 00 0f 1f 80 00 00 00 00
>   RSP: 0018:ffffc900002dfa20 EFLAGS: 00010282
>   RAX: 0000000000000000 RBX: ffffffffc0107000 RCX: 0000000000000006
>   RDX: 0000000000000007 RSI: 0000000000000092 RDI: ffff88813bb17540
>   RBP: 00000000fe000000 R08: 000000000000015f R09: 000000000000000a
>   R10: 000000000000000a R11: ffffc900002df8da R12: 0000000000002000
>   R13: 0000000000000000 R14: 0000000000000002 R15: ffffffff822da3a0
>   FS:  000072ecce666940(0000) GS:ffff88813bb00000(0000) knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 0000785be7346d20 CR3: 000000000d872001 CR4: 00000000003606e0
>   Call Trace:
>    ? pmc_core_probe+0x87/0x2d0 [intel_pmc_core]
>    pmc_core_probe+0x87/0x2d0 [intel_pmc_core]
>    platform_drv_probe+0x35/0x80
>    really_probe+0x298/0x3c0
>    driver_probe_device+0x7a/0x100
>    ? driver_allows_async_probing+0x50/0x50
>    bus_for_each_drv+0x8f/0xd0
>    __device_attach+0xf0/0x170
>    bus_probe_device+0x8e/0xa0
>    device_add+0x692/0x7e0
>    platform_device_add+0xe9/0x240
>    ? 0xffffffffc00ec000
>    do_one_initcall+0x59/0x214
>    do_init_module+0x5c/0x230
>    load_module+0x258d/0x2840
>    ? __do_sys_finit_module+0xbb/0x120
>    __do_sys_finit_module+0xbb/0x120
>    do_syscall_64+0x5f/0x1a0
>    entry_SYSCALL_64_after_hwframe+0x44/0xa9
>   RIP: 0033:0x72eccf662fad
>   Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ab 9e 0c 00 f7 d8 64 89 01 48
>   RSP: 002b:00007ffd3710d018 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
>   RAX: ffffffffffffffda RBX: 000060ab8fda2530 RCX: 000072eccf662fad
>   RDX: 0000000000000000 RSI: 000072eccf2bd84d RDI: 0000000000000017
>   RBP: 0000000000020000 R08: 0000000000000000 R09: 0000000000000007
>   R10: 0000000000000017 R11: 0000000000000246 R12: 000072eccf2bd84d
>   R13: 0000000000000000 R14: 000060ab8fd9b5e0 R15: 0000000000000007
>   ---[ end trace 5e5421608729d6f4 ]---
>
> This issue appears to manifest itself because of the following fallback
> mechanism in the driver:
>
>         if (lpit_read_residency_count_address(&slp_s0_addr))
>                 pmcdev->base_addr = PMC_BASE_ADDR_DEFAULT;
>
> The validity of address PMC_BASE_ADDR_DEFAULT (i.e., 0xFE000000) is not
> verified by the driver, which is what this patch introduces. With this
> patch, if address PMC_BASE_ADDR_DEFAULT is in RAM, then the driver will
> not attempt to ioremap the aforementioned address.
>

Pushed to my review and testing queue, thanks!

P.S. I cut unnecessary output off.

> Signed-off-by: M. Vefa Bicakci <m.v.b@runbox.com>
> ---
>  drivers/platform/x86/intel_pmc_core.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/platform/x86/intel_pmc_core.c b/drivers/platform/x86/intel_pmc_core.c
> index c510d0d72475..3b6b8dcc4767 100644
> --- a/drivers/platform/x86/intel_pmc_core.c
> +++ b/drivers/platform/x86/intel_pmc_core.c
> @@ -878,10 +878,14 @@ static int pmc_core_probe(struct platform_device *pdev)
>         if (pmcdev->map == &spt_reg_map && !pci_dev_present(pmc_pci_ids))
>                 pmcdev->map = &cnp_reg_map;
>
> -       if (lpit_read_residency_count_address(&slp_s0_addr))
> +       if (lpit_read_residency_count_address(&slp_s0_addr)) {
>                 pmcdev->base_addr = PMC_BASE_ADDR_DEFAULT;
> -       else
> +
> +               if (page_is_ram(PHYS_PFN(pmcdev->base_addr)))
> +                       return -ENODEV;
> +       } else {
>                 pmcdev->base_addr = slp_s0_addr - pmcdev->map->slp_s0_offset;
> +       }
>
>         pmcdev->regbase = ioremap(pmcdev->base_addr,
>                                   pmcdev->map->regmap_length);
> --
> 2.21.0
>


-- 
With Best Regards,
Andy Shevchenko