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Violators will be prosecuted for from ; Wed, 6 Dec 2017 14:17:28 -0500 From: Michael Roth Date: Wed, 6 Dec 2017 13:16:18 -0600 In-Reply-To: <20171206191648.18208-1-mdroth@linux.vnet.ibm.com> References: <20171206191648.18208-1-mdroth@linux.vnet.ibm.com> Message-Id: <20171206191648.18208-26-mdroth@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH 25/55] exec: add page_mask for flatview_do_translate List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Peter Xu , Maxime Coquelin , Paolo Bonzini From: Peter Xu The function is originally used for flatview_space_translate() and what we care about most is (xlat, plen) range. However for iotlb requests, we don't really care about "plen", but the size of the page that "xlat" is located on. While, plen cannot really contain this information. A simple example to show why "plen" is not good for IOTLB translations: E.g., for huge pages, it is possible that guest mapped 1G huge page on device side that used this GPA range: 0x100000000 - 0x13fffffff Then let's say we want to translate one IOVA that finally mapped to GPA 0x13ffffe00 (which is located on this 1G huge page). Then here we'll get: (xlat, plen) = (0x13fffe00, 0x200) So the IOTLB would be only covering a very small range since from "plen" (which is 0x200 bytes) we cannot tell the size of the page. Actually we can really know that this is a huge page - we just throw the information away in flatview_do_translate(). This patch introduced "page_mask" optional parameter to capture that page mask info. Also, I made "plen" an optional parameter as well, with some comments for the whole function. No functional change yet. Signed-off-by: Peter Xu Signed-off-by: Maxime Coquelin Message-Id: <20171010094247.10173-2-maxime.coquelin@redhat.com> Signed-off-by: Paolo Bonzini (cherry picked from commit d5e5fafd11be4458443c43f19c1ebdd24d99a751) Signed-off-by: Michael Roth --- exec.c | 51 +++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 45 insertions(+), 6 deletions(-) diff --git a/exec.c b/exec.c index b1f29d35d8..2fd65dc3f2 100644 --- a/exec.c +++ b/exec.c @@ -468,11 +468,29 @@ address_space_translate_internal(AddressSpaceDispatch *d, hwaddr addr, hwaddr *x return section; } -/* Called from RCU critical section */ +/** + * flatview_do_translate - translate an address in FlatView + * + * @fv: the flat view that we want to translate on + * @addr: the address to be translated in above address space + * @xlat: the translated address offset within memory region. It + * cannot be @NULL. + * @plen_out: valid read/write length of the translated address. It + * can be @NULL when we don't care about it. + * @page_mask_out: page mask for the translated address. This + * should only be meaningful for IOMMU translated + * addresses, since there may be huge pages that this bit + * would tell. It can be @NULL if we don't care about it. + * @is_write: whether the translation operation is for write + * @is_mmio: whether this can be MMIO, set true if it can + * + * This function is called from RCU critical section + */ static MemoryRegionSection flatview_do_translate(FlatView *fv, hwaddr addr, hwaddr *xlat, - hwaddr *plen, + hwaddr *plen_out, + hwaddr *page_mask_out, bool is_write, bool is_mmio, AddressSpace **target_as) @@ -481,11 +499,17 @@ static MemoryRegionSection flatview_do_translate(FlatView *fv, MemoryRegionSection *section; IOMMUMemoryRegion *iommu_mr; IOMMUMemoryRegionClass *imrc; + hwaddr page_mask = (hwaddr)(-1); + hwaddr plen = (hwaddr)(-1); + + if (plen_out) { + plen = *plen_out; + } for (;;) { section = address_space_translate_internal( flatview_to_dispatch(fv), addr, &addr, - plen, is_mmio); + &plen, is_mmio); iommu_mr = memory_region_get_iommu(section->mr); if (!iommu_mr) { @@ -497,7 +521,8 @@ static MemoryRegionSection flatview_do_translate(FlatView *fv, IOMMU_WO : IOMMU_RO); addr = ((iotlb.translated_addr & ~iotlb.addr_mask) | (addr & iotlb.addr_mask)); - *plen = MIN(*plen, (addr | iotlb.addr_mask) - addr + 1); + page_mask &= iotlb.addr_mask; + plen = MIN(plen, (addr | iotlb.addr_mask) - addr + 1); if (!(iotlb.perm & (1 << is_write))) { goto translate_fail; } @@ -508,6 +533,19 @@ static MemoryRegionSection flatview_do_translate(FlatView *fv, *xlat = addr; + if (page_mask == (hwaddr)(-1)) { + /* Not behind an IOMMU, use default page size. */ + page_mask = ~TARGET_PAGE_MASK; + } + + if (page_mask_out) { + *page_mask_out = page_mask; + } + + if (plen_out) { + *plen_out = plen; + } + return *section; translate_fail: @@ -526,7 +564,7 @@ IOMMUTLBEntry address_space_get_iotlb_entry(AddressSpace *as, hwaddr addr, /* This can never be MMIO. */ section = flatview_do_translate(address_space_to_flatview(as), addr, - &xlat, &plen, is_write, false, &as); + &xlat, &plen, NULL, is_write, false, &as); /* Illegal translation */ if (section.mr == &io_mem_unassigned) { @@ -570,7 +608,8 @@ MemoryRegion *flatview_translate(FlatView *fv, hwaddr addr, hwaddr *xlat, AddressSpace *as = NULL; /* This can be MMIO, so setup MMIO bit. */ - section = flatview_do_translate(fv, addr, xlat, plen, is_write, true, &as); + section = flatview_do_translate(fv, addr, xlat, plen, NULL, + is_write, true, &as); mr = section.mr; if (xen_enabled() && memory_access_is_direct(mr, is_write)) { -- 2.11.0