Re: [PATCH V4 15/23] acpi, mcfg: Implement two calls that might be used to inject/remove MCFG region.

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On 10.02.2016 15:06, Lorenzo Pieralisi wrote:
On Thu, Feb 04, 2016 at 06:28:53PM +0100, Tomasz Nowicki wrote:
>Lets abstract two calls which allow to inject and remove MCFG regions
>which may come from DSDT table. These calls will be used for x86 and ARM64
>PCI host bridge driver in the later patches.
>
>Signed-off-by: Tomasz Nowicki<tn@xxxxxxxxxxxx>
>Tested-by: Duc Dang<dhdang@xxxxxxx>
>Tested-by: Dongdong Liu<liudongdong3@xxxxxxxxxx>
>Tested-by: Hanjun Guo<hanjun.guo@xxxxxxxxxx>
>Tested-by: Graeme Gregory<graeme.gregory@xxxxxxxxxx>
>Tested-by: Sinan Kaya<okaya@xxxxxxxxxxxxxx>
>---
>  drivers/acpi/mcfg.c      | 38 ++++++++++++++++++++++++++++++++++++++
>  include/linux/pci-acpi.h |  9 +++++++++
>  2 files changed, 47 insertions(+)
>
>diff --git a/drivers/acpi/mcfg.c b/drivers/acpi/mcfg.c
>index 3e1e7be..dca4c4e 100644
>--- a/drivers/acpi/mcfg.c
>+++ b/drivers/acpi/mcfg.c
>@@ -10,6 +10,7 @@
>  #include <linux/acpi.h>
>  #include <linux/ecam.h>
>  #include <linux/pci.h>
>+#include <linux/pci-acpi.h>
>
>  #define	PREFIX	"MCFG: "
>
>@@ -77,6 +78,43 @@ int __init acpi_parse_mcfg(struct acpi_table_header *header)
>  	return 0;
>  }
>
>+int pci_mmcfg_setup_map(struct acpi_pci_root_info *ci)
>+{
>+	struct pci_mmcfg_region *cfg;
>+	struct acpi_pci_root *root;
>+	int seg, start, end, err;
>+
>+	root = ci->root;
>+	seg = root->segment;
>+	start = root->secondary.start;
>+	end = root->secondary.end;
>+
>+	cfg = pci_mmconfig_lookup(seg, start);
>+	if (cfg)
>+		return 0;
>+
>+	cfg = pci_mmconfig_alloc(seg, start, end, root->mcfg_addr);
>+	if (!cfg)
>+		return -ENOMEM;
>+
>+	err = pci_mmconfig_inject(cfg);
>+	return err;
When you integrate Jayachandran's patch this whole function will
become a pci_mmconfig_insert() and that's where hot_added should
be set.

>+}
>+
>+void pci_mmcfg_teardown_map(struct acpi_pci_root_info *ci)
>+{
>+	struct acpi_pci_root *root = ci->root;
>+	struct pci_mmcfg_region *cfg;
>+
>+	cfg = pci_mmconfig_lookup(root->segment, root->secondary.start);
>+	if (!cfg)
>+		return;
>+
>+	if (cfg->hot_added)
Move the hot_added check in pci_mmconfig_delete() (that does the look
up again), we do not want to carry out pci_mmconfig_lookup only to
check that flag here (and we miss rcu locking for the look-up BTW).

Makes sense to me, I will follow your suggestion.

Thanks,
Tomasz
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