[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v6 02/11] arch, arm: add consistency check to REMOVE p2m changes
Currently, the REMOVE case of the switch in apply_p2m_changes() does not perform any consistency check on the mapping to be removed. More in detail, the code does not check if the guest address to be unmapped is actually mapped to the machine address given as a parameter. This commit attempts to add the above-described consistency check to the REMOVE path of apply_p2m_changes(). This is instrumental to one of the following commits which implements the possibility to trigger the removal of p2m ranges via the memory_mapping DOMCTL for ARM. Signed-off-by: Arianna Avanzini <avanzini.arianna@xxxxxxxxx> Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> Cc: Dario Faggioli <dario.faggioli@xxxxxxxxxx> Cc: Paolo Valente <paolo.valente@xxxxxxxxxx> Cc: Julien Grall <julien.grall@xxxxxxxxxx> Cc: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx> Cc: Jan Beulich <JBeulich@xxxxxxxx> Cc: Keir Fraser <keir@xxxxxxx> Cc: Tim Deegan <tim@xxxxxxx> Cc: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx> Cc: Eric Trudeau <etrudeau@xxxxxxxxxxxx> Cc: Viktor Kleinik <viktor.kleinik@xxxxxxxxxxxxxxx> --- v6: - Don't update "count" on REMOVE as it is only used inside the RELINQUISH case of the switch in apply_p2m_changes(). - Return with an error if removal of a page fails instead of just skipping the page. v5: - Do not use a temporary variable to hold the machine address: use the "maddr" function parameter itself. - Increment the machine address also when first and second level mappings are not valid. - Get the actual machine frame number mapped to the guest frame number given as parameter to the function directly in the REMOVE case of the switch construct, as it might not be valid in other cases and its value might be uncorrectly used in the future. - Remove useless and/or harmful ASSERT; check however if the mapping is valid and skip the page if it is not. v4: - Remove useless and slow lookup and use already-available data from pte instead. - Correctly increment the local variable used to keep the machine address whose mapping is currently being removed. - Return with an error upon finding a mismatch between the actual machine address mapped to the guest address and the machine address passed as parameter, instead of just skipping the page. --- xen/arch/arm/p2m.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c index 403fd89..7f03aa7 100644 --- a/xen/arch/arm/p2m.c +++ b/xen/arch/arm/p2m.c @@ -319,6 +319,7 @@ static int apply_p2m_changes(struct domain *d, if ( !populate ) { addr = (addr + FIRST_SIZE) & FIRST_MASK; + maddr = (maddr + FIRST_SIZE) & FIRST_MASK; continue; } @@ -345,6 +346,7 @@ static int apply_p2m_changes(struct domain *d, if ( !populate ) { addr = (addr + SECOND_SIZE) & SECOND_MASK; + maddr = (maddr + SECOND_SIZE) & SECOND_MASK; continue; } @@ -406,12 +408,26 @@ static int apply_p2m_changes(struct domain *d, { pte = mfn_to_p2m_entry(maddr >> PAGE_SHIFT, mattr, t); write_pte(&third[third_table_offset(addr)], pte); - maddr += PAGE_SIZE; } break; - case RELINQUISH: case REMOVE: { + unsigned long mfn = pte.p2m.base; + + /* + * Ensure that the guest address given as argument to + * this function is actually mapped to the specified + * machine address. maddr here is the machine address + * given to the function, while mfn is the machine + * frame number actually mapped to the guest address: + * check if the two correspond. + */ + if ( !pte.p2m.valid || maddr != pfn_to_paddr(mfn) ) + return -EINVAL; + } + /* fall through */ + case RELINQUISH: + { if ( !pte.p2m.valid ) { count++; @@ -425,7 +441,6 @@ static int apply_p2m_changes(struct domain *d, count++; } break; - case CACHEFLUSH: { if ( !pte.p2m.valid || !p2m_is_ram(pte.p2m.type) ) @@ -450,6 +465,7 @@ static int apply_p2m_changes(struct domain *d, /* Got the next page */ addr += PAGE_SIZE; + maddr += PAGE_SIZE; } if ( flush ) -- 1.9.1 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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