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From: Roger Pau Monne <roger.pau@citrix.com>
To: <xen-devel@lists.xenproject.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	Ian Jackson <ian.jackson@eu.citrix.com>, Wei Liu <wl@xen.org>,
	Jan Beulich <jbeulich@suse.com>,
	Roger Pau Monne <roger.pau@citrix.com>
Subject: [Xen-devel] [PATCH] x86/hvmloader: align BAR position to 4K
Date: Tue, 14 Jan 2020 19:13:45 +0100
Message-ID: <20200114181345.27565-1-roger.pau@citrix.com> (raw)

When placing BARs with sizes smaller than 4K multiple BARs can end
up mapped to the same guest physical address, and thus won't work

Align all BARs placement to 4K in hvmloader to prevent such

Note that the guest can still move the BARs around and create this
collisions, and that BARs not filling up a physical page might leak
access to other MMIO regions placed in the same host physical page.

This is however no worse than what's currently done, and hence should
be considered an improvement over the current state.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
 tools/firmware/hvmloader/pci.c  | 4 ++++
 tools/firmware/hvmloader/util.h | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/tools/firmware/hvmloader/pci.c b/tools/firmware/hvmloader/pci.c
index 0b708bf578..c433b34cd6 100644
--- a/tools/firmware/hvmloader/pci.c
+++ b/tools/firmware/hvmloader/pci.c
@@ -489,6 +489,10 @@ void pci_setup(void)
         resource->base = base;
+        if ( (bar_data & PCI_BASE_ADDRESS_SPACE) ==
+            resource->base = ROUNDUP(resource->base, PAGE_SIZE);
         pci_writel(devfn, bar_reg, bar_data);
         if (using_64bar)
             pci_writel(devfn, bar_reg + 4, bar_data_upper);
diff --git a/tools/firmware/hvmloader/util.h b/tools/firmware/hvmloader/util.h
index 7bca6418d2..b5554b5844 100644
--- a/tools/firmware/hvmloader/util.h
+++ b/tools/firmware/hvmloader/util.h
@@ -51,6 +51,8 @@ void __bug(char *file, int line) __attribute__((noreturn));
 #define MB(mb) (mb##ULL << 20)
 #define GB(gb) (gb##ULL << 30)
+#define ROUNDUP(x, a) (((x) + (a) - 1) & ~((a) - 1))
 static inline int test_bit(unsigned int b, const void *p)
     return !!(((const uint8_t *)p)[b>>3] & (1u<<(b&7)));

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Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-14 18:13 Roger Pau Monne [this message]
2020-01-16 10:56 ` Jan Beulich
2020-01-16 19:57 ` Jason Andryuk

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