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| author | Shuah Khan <skhan@linuxfoundation.org> | 2020-01-23 15:32:14 -0700 |
|---|---|---|
| committer | Joerg Roedel <jroedel@suse.de> | 2020-01-24 15:28:40 +0100 |
| commit | 8c17bbf6c8f70058a66305f2e1982552e6ea7f47 (patch) | |
| tree | 8d9f6685bd20bd711f9f61cb6d892cac47bdd38e | |
| parent | bf708cfb2f4811d1948a88c41ab96587e84ad344 (diff) | |
| download | linux-8c17bbf6c8f70058a66305f2e1982552e6ea7f47.tar.bz2 | |
iommu/amd: Fix IOMMU perf counter clobbering during init
init_iommu_perf_ctr() clobbers the register when it checks write access
to IOMMU perf counters and fails to restore when they are writable.
Add save and restore to fix it.
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Fixes: 30861ddc9cca4 ("perf/x86/amd: Add IOMMU Performance Counter resource management")
Reviewed-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Tested-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
| -rw-r--r-- | drivers/iommu/amd_iommu_init.c | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c index 568c52317757..483f7bc379fa 100644 --- a/drivers/iommu/amd_iommu_init.c +++ b/drivers/iommu/amd_iommu_init.c @@ -1655,27 +1655,39 @@ static int iommu_pc_get_set_reg(struct amd_iommu *iommu, u8 bank, u8 cntr, static void init_iommu_perf_ctr(struct amd_iommu *iommu) { struct pci_dev *pdev = iommu->dev; - u64 val = 0xabcd, val2 = 0; + u64 val = 0xabcd, val2 = 0, save_reg = 0; if (!iommu_feature(iommu, FEATURE_PC)) return; amd_iommu_pc_present = true; + /* save the value to restore, if writable */ + if (iommu_pc_get_set_reg(iommu, 0, 0, 0, &save_reg, false)) + goto pc_false; + /* Check if the performance counters can be written to */ if ((iommu_pc_get_set_reg(iommu, 0, 0, 0, &val, true)) || (iommu_pc_get_set_reg(iommu, 0, 0, 0, &val2, false)) || - (val != val2)) { - pci_err(pdev, "Unable to write to IOMMU perf counter.\n"); - amd_iommu_pc_present = false; - return; - } + (val != val2)) + goto pc_false; + + /* restore */ + if (iommu_pc_get_set_reg(iommu, 0, 0, 0, &save_reg, true)) + goto pc_false; pci_info(pdev, "IOMMU performance counters supported\n"); val = readl(iommu->mmio_base + MMIO_CNTR_CONF_OFFSET); iommu->max_banks = (u8) ((val >> 12) & 0x3f); iommu->max_counters = (u8) ((val >> 7) & 0xf); + + return; + +pc_false: + pci_err(pdev, "Unable to read/write to IOMMU perf counter.\n"); + amd_iommu_pc_present = false; + return; } static ssize_t amd_iommu_show_cap(struct device *dev, |