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From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     "M. Vefa Bicakci" <m.v.b@runbox.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Sasha Levin <sashal@kernel.org>,
        platform-driver-x86@vger.kernel.org
Subject: [PATCH AUTOSEL 5.3 171/203] platform/x86: intel_pmc_core: Do not ioremap RAM
Date:   Sun, 22 Sep 2019 14:43:17 -0400
Message-Id: <20190922184350.30563-171-sashal@kernel.org>
In-Reply-To: <20190922184350.30563-1-sashal@kernel.org>
References: <20190922184350.30563-1-sashal@kernel.org>
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From: "M. Vefa Bicakci" <m.v.b@runbox.com>

[ Upstream commit 7d505758b1e556cdf65a5e451744fe0ae8063d17 ]

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:

  ioremap on RAM at 0x00000000fe000000 - 0x00000000fe001fff
  WARNING: CPU: 1 PID: 434 at arch/x86/mm/ioremap.c:186 __ioremap_caller.constprop.0+0x2aa/0x2c0
...
  Call Trace:
   ? pmc_core_probe+0x87/0x2d0 [intel_pmc_core]
   pmc_core_probe+0x87/0x2d0 [intel_pmc_core]

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>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 c510d0d724759..3b6b8dcc47678 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);
-- 
2.20.1