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lguest: make check_gpte et. al return bool.
This is a bit neater: we can immediately return if a PTE/PGD/PMD entry is invalid (which also kills the guest). It means we don't risk using invalid entries as we reshuffle the code. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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parent
93a2cdff98
commit
e1d12606f7
1 changed files with 23 additions and 10 deletions
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@ -259,26 +259,35 @@ static void release_pte(pte_t pte)
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}
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/*:*/
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static void check_gpte(struct lg_cpu *cpu, pte_t gpte)
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static bool check_gpte(struct lg_cpu *cpu, pte_t gpte)
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{
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if ((pte_flags(gpte) & _PAGE_PSE) ||
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pte_pfn(gpte) >= cpu->lg->pfn_limit)
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pte_pfn(gpte) >= cpu->lg->pfn_limit) {
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kill_guest(cpu, "bad page table entry");
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return false;
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}
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return true;
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}
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static void check_gpgd(struct lg_cpu *cpu, pgd_t gpgd)
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static bool check_gpgd(struct lg_cpu *cpu, pgd_t gpgd)
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{
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if ((pgd_flags(gpgd) & ~CHECK_GPGD_MASK) ||
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(pgd_pfn(gpgd) >= cpu->lg->pfn_limit))
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(pgd_pfn(gpgd) >= cpu->lg->pfn_limit)) {
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kill_guest(cpu, "bad page directory entry");
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return false;
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}
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return true;
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}
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#ifdef CONFIG_X86_PAE
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static void check_gpmd(struct lg_cpu *cpu, pmd_t gpmd)
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static bool check_gpmd(struct lg_cpu *cpu, pmd_t gpmd)
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{
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if ((pmd_flags(gpmd) & ~_PAGE_TABLE) ||
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(pmd_pfn(gpmd) >= cpu->lg->pfn_limit))
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(pmd_pfn(gpmd) >= cpu->lg->pfn_limit)) {
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kill_guest(cpu, "bad page middle directory entry");
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return false;
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}
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return true;
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}
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#endif
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@ -336,7 +345,8 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
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return false;
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}
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/* We check that the Guest pgd is OK. */
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check_gpgd(cpu, gpgd);
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if (!check_gpgd(cpu, gpgd))
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return false;
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/*
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* And we copy the flags to the shadow PGD entry. The page
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* number in the shadow PGD is the page we just allocated.
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@ -372,7 +382,8 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
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}
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/* We check that the Guest pmd is OK. */
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check_gpmd(cpu, gpmd);
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if (!check_gpmd(cpu, gpmd))
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return false;
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/*
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* And we copy the flags to the shadow PMD entry. The page
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@ -421,7 +432,8 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
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* Check that the Guest PTE flags are OK, and the page number is below
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* the pfn_limit (ie. not mapping the Launcher binary).
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*/
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check_gpte(cpu, gpte);
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if (!check_gpte(cpu, gpte))
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return false;
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/* Add the _PAGE_ACCESSED and (for a write) _PAGE_DIRTY flag */
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gpte = pte_mkyoung(gpte);
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@ -857,7 +869,8 @@ static void do_set_pte(struct lg_cpu *cpu, int idx,
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* micro-benchmark.
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*/
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if (pte_flags(gpte) & (_PAGE_DIRTY | _PAGE_ACCESSED)) {
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check_gpte(cpu, gpte);
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if (!check_gpte(cpu, gpte))
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return;
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set_pte(spte,
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gpte_to_spte(cpu, gpte,
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pte_flags(gpte) & _PAGE_DIRTY));
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